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Articles 2161 - 2190 of 3773

Full-Text Articles in Population Biology

Winter Freeze Decreases The Emergence Of Fauna And Flora In California Vernal Pools, Korena S. Hendryx, Jamie Kneitel Aug 2015

Winter Freeze Decreases The Emergence Of Fauna And Flora In California Vernal Pools, Korena S. Hendryx, Jamie Kneitel

STAR Program Research Presentations

Impacts of global climate change is observed in many ecological systems. Temporary aquatic ecosystems, including California vernal pools, are especially sensitive to climatic variation, but most species are adapted to the annual fluctuations in precipitation and temperature. Since vernal pools experience an inundation and desiccation every year, species that occupy the ecosystem have adaptations to this cycle. Many species survive drought by creating resting eggs to then re-emerge upon inundation However, climate changes outside the typical range may have deleterious effects on these populations. Moreover, climate variation can have secondary effects on the community. For example, the amount of precipitation …


Effects Of Land Management On Mammalian Species Abundance And Richness Among Four Sites In West-Central Georgia, Kelsey A. Champagne Aug 2015

Effects Of Land Management On Mammalian Species Abundance And Richness Among Four Sites In West-Central Georgia, Kelsey A. Champagne

Theses and Dissertations

No abstract provided.


A Search For Parent-Of-Origin Effects On Honey Bee Gene Expression, Sarah D. Kocher, Jennifer M. Tsuruda, Joshua D. Gibson, Christine M. Emore, Miguel E. Arechavaleta-Velasco, David C. Queller, Joan E. Strassmann, Christina M. Grozinger, Michael R. Gribskov, Phillip San Miguel, Rick Westerman, Greg J. Hunt Aug 2015

A Search For Parent-Of-Origin Effects On Honey Bee Gene Expression, Sarah D. Kocher, Jennifer M. Tsuruda, Joshua D. Gibson, Christine M. Emore, Miguel E. Arechavaleta-Velasco, David C. Queller, Joan E. Strassmann, Christina M. Grozinger, Michael R. Gribskov, Phillip San Miguel, Rick Westerman, Greg J. Hunt

Biology Faculty Research

Parent-specific gene expression (PSGE) is little known outside of mammals and plants. PSGE occurs when the expression level of a gene depends on whether an allele was inherited from the mother or the father. Kin selection theory predicts that there should be extensive PSGE in social insects because social insect parents can gain inclusive fitness benefits by silencing parental alleles in female offspring. We searched for evidence of PSGE in honey bees using transcriptomes from reciprocal crosses between European and Africanized strains. We found 46 transcripts with significant parent-of-origin effects on gene expression, many of which overexpressed the maternal allele. …


Habitat Use By Spruce Grouse In A Fragmented System, Laurel A. Hill Aug 2015

Habitat Use By Spruce Grouse In A Fragmented System, Laurel A. Hill

All NMU Master's Theses

The spruce grouse is a boreal obligate species that has been protected in Michigan since 1915 (Ammann 1963). Despite protection, the status of spruce grouse is uncertain in Michigan and other parts of the Midwest, and there have been few attempts at large-scale surveys or monitoring (Williamson et al. 2008). I studied a population of spruce grouse near the southern edge of their range on the Yellow Dog Plains in Marquette County, Michigan.

I investigated fecal pellet counts as a possible method to assess spruce grouse presence and habitat use. My results validated the use of fecal pellet occurrence as …


Identifying The Geographic Origins For The Introduction Of Taeniatherum Caput-Medusae Subsp. Asperum (Medusahead) In The Western United States, Shane Kurtis Skaar Aug 2015

Identifying The Geographic Origins For The Introduction Of Taeniatherum Caput-Medusae Subsp. Asperum (Medusahead) In The Western United States, Shane Kurtis Skaar

Boise State University Theses and Dissertations

The use of molecular markers can provide insights into the demographic and evolutionary processes that have shaped the genetic diversity of native populations and can be used to identify an invasive species’ geographic origins. Taeniatherum caput-medusae subsp. asperum (medusahead) is a cleistogamous, diploid, annual grass native toEurasia that is now invasive in the western United States (U.S.). Enzyme electrophoresis methods (allozymes) have previously been used to analyze both native and invasive populations of medusahead. Results from these studies suggest that the invasion of medusahead in the westernU.S. stems from multiple introduction events. In addition, 10 of 34 populations from across …


Mammalian Records From Southwestern Kansas And Northwestern Oklahoma, Including The First Record Of Crawford’S Desert Shrew (Notiosorex Crawfordi) From Kansas, Cody A. Dreier, Keith Geluso, Jennifer D. Frisch, Brittney N. Adams, Alyx R. Lingenfelter, Anthony E. Bridger, Patricia Freeman, Cliff Lemen, Jeremy A. White, Brett R. Andersen, Hans W. Otto, Curtis J. Schmidt Jul 2015

Mammalian Records From Southwestern Kansas And Northwestern Oklahoma, Including The First Record Of Crawford’S Desert Shrew (Notiosorex Crawfordi) From Kansas, Cody A. Dreier, Keith Geluso, Jennifer D. Frisch, Brittney N. Adams, Alyx R. Lingenfelter, Anthony E. Bridger, Patricia Freeman, Cliff Lemen, Jeremy A. White, Brett R. Andersen, Hans W. Otto, Curtis J. Schmidt

School of Natural Resources: Faculty Publications

Mammalian distributions are constantly changing. Some distributional shifts reflect habitat change, climate change, and human transplantations; thus, such shifts are due to actual expansions or contractions of populations. However, other species ranges that appear to shift as the result of new records being added to known distributional limits actually might reflect populations that previously were undetected due to a lack of past surveys or species that are difficult to detect. In 2013, multiple techniques were employed to document mammalian distributional records in southwestern Kansas and northwestern Oklahoma. We discovered three new county records in Morton County, Kansas (Crawford’s Desert Shrew, …


Reproductive Timing Of Erimystax Insignis (Blotched Chub) In The Flint River Of North Alabama, Bruce Stallsmith, Josh Mann, Candice Allen Jul 2015

Reproductive Timing Of Erimystax Insignis (Blotched Chub) In The Flint River Of North Alabama, Bruce Stallsmith, Josh Mann, Candice Allen

Southeastern Fishes Council Proceedings

Important details of the reproductive ecology of many freshwater fishes of the species-rich southeastern United States are still poorly known. One such species is Erimystax insignis (Blotched Chub), whose range includes the Tennessee River drainage in northern Alabama, USA. To determine timing and patterns of reproductive effort, collections were made monthly of as many as 30 individuals from August 2011 through July 2012 from a 14 km stretch of the Flint River in Madison County, Alabama. Female and male gonadosomatic index (GSI) and ovarian development data indicate that reproductive activity for the species peaks from March through May. Ripe and …


Unowned Cat Management In The State Of Ohio: Elements Of Best Practice In Public-Private Collaborative Efforts, Daniel D. Spehar Jul 2015

Unowned Cat Management In The State Of Ohio: Elements Of Best Practice In Public-Private Collaborative Efforts, Daniel D. Spehar

HSU STUDENT THESES AND CAPSTONE PROJECTS

A contentious debate over the management of free-roaming cat populations is ongoing. Nevertheless, disparate groups of stakeholders share a common goal of fewer community cats. Unowned cat management typically necessitates a choice between utilization of lethal or non-lethal measures. Research has indicated strong public support for employment of non-lethal methods, like trap-neuter-return (TNR). Collaborative TNR programs are experiencing success in a growing number of communities. The purpose of this exploratory study was to identify new or underutilized public-private collaborative practices, and associated elemental factors, that have the potential to be used as—or incorporated into—templates of best practice for the non-lethal …


Seasonal Dynamics And Micro-Climatic Preference Of Two Alpine Endemic Hypogean Beetles, Stefano Mammola, Elena Piano, Pier Mauro Giachino, Marco Isaia Jun 2015

Seasonal Dynamics And Micro-Climatic Preference Of Two Alpine Endemic Hypogean Beetles, Stefano Mammola, Elena Piano, Pier Mauro Giachino, Marco Isaia

International Journal of Speleology

Hypogean beetles generally live in stable environments, characterized by constant temperature and high relative humidity. Changes in the underground microclimatic conditions generally induce local migrations of the beetles through the hypogean environment in search of suitable microhabitats. We studied the seasonal dynamics and the micro-climatic preference of two Alpine endemic hypogean beetles - Sphodropsis ghilianii (Coleoptera, Carabidae) and Dellabeffaella roccae (Coleoptera, Cholevidae) - in the hypogean complex of Pugnetto (Graian Alps, Italy). We surveyed the two species for one year, using baited pitfall traps and measuring temperature and humidity along the two main caves. We used logistic regression mixed models …


Fuels And Fires Influence Vegetation Via Above- And Belowground Pathways In A High-Diversity Plant Community, Paul R. Gagnon, Heather A. Passmore, Matthew Slocum, Jonathan A. Myers, Kyle E. Harms, William J. Platt, C.E. Timothy Paine Jun 2015

Fuels And Fires Influence Vegetation Via Above- And Belowground Pathways In A High-Diversity Plant Community, Paul R. Gagnon, Heather A. Passmore, Matthew Slocum, Jonathan A. Myers, Kyle E. Harms, William J. Platt, C.E. Timothy Paine

Biology Faculty Research

  1. Fire strongly influences plant populations and communities around the world, making it an important agent of plant evolution. Fire influences vegetation through multiple pathways, both above- and belowground. Few studies have yet attempted to tie these pathways together in a mechanistic way through soil heating even though the importance of soil heating for plants in fire-prone ecosystems is increasingly recognized.
  2. Here we combine an experimental approach with structural equation modelling (SEM) to simultaneously examine multiple pathways through which fire might influence herbaceous vegetation. In a high-diversity longleaf pine groundcover community in Louisiana, USA, we manipulated fine-fuel biomass and monitored the …


Genomic Signatures Of Cooperation And Conflict In The Social Amoeba, Elizabeth A. Ostrowski, Yufeng Shen, Xiangjun Tian, Richard Sucgang, Huaiyang Jiang, Jiaxin Qu, Mariko Katoh-Kurasawa, Debra A. Brock, Christopher Dinh, Fremiet Lara-Garduno, Sandra L. Lee, Christie L. Kovar, Huyen H. Dinh, Viktoriya Korchina, Laronda Jackson, Shobha Patil, Yi Han, Lesley Chaboub, Gad Shaulsky, Donna M. Muzny, Kim C. Worley, Richard A. Gibbs, Stephen Richards, Adam Kuspa, Joan E. Strassmann, David C. Queller Jun 2015

Genomic Signatures Of Cooperation And Conflict In The Social Amoeba, Elizabeth A. Ostrowski, Yufeng Shen, Xiangjun Tian, Richard Sucgang, Huaiyang Jiang, Jiaxin Qu, Mariko Katoh-Kurasawa, Debra A. Brock, Christopher Dinh, Fremiet Lara-Garduno, Sandra L. Lee, Christie L. Kovar, Huyen H. Dinh, Viktoriya Korchina, Laronda Jackson, Shobha Patil, Yi Han, Lesley Chaboub, Gad Shaulsky, Donna M. Muzny, Kim C. Worley, Richard A. Gibbs, Stephen Richards, Adam Kuspa, Joan E. Strassmann, David C. Queller

Biology Faculty Research

    • Molecular evolution analyses reveal the history of social conflict
    • Genes that mediate social conflict show signatures of frequency-dependent selection
    • Balanced polymorphisms suggest that cheating may be stable and endemic

Cooperative systems are susceptible to invasion by selfish individuals that profit from receiving the social benefits but fail to contribute. These so-called "cheaters" can have a fitness advantage in the laboratory, but it is unclear whether cheating provides an important selective advantage in nature. We used a population genomic approach to examine the history of genes involved in cheating behaviors in the social amoeba Dictyostelium discoideum, testing whether these genes experience …


The Characterization Of A Vital Wisconsin Waterway: A Biological Assessment Of The Lower Fox River From 2006-2014, Emily L. Kiehnau Jun 2015

The Characterization Of A Vital Wisconsin Waterway: A Biological Assessment Of The Lower Fox River From 2006-2014, Emily L. Kiehnau

Lawrence University Honors Projects

The Lower Fox River has historically been used as a navigational crossroads, a waste disposal system, and source of hydroelectric power. Over the years, heavy use of the river has negatively affected water quality and the overall health of the system. Unhealthy rivers cannot function properly. Biological assessment based on animal surveys are often used to determine river health. I used data from the Lawrence University and Fox River Navigational System Authority invasive species-monitoring project to explore how the distribution of animals in the Fox River has changed over time and across locations. Monitoring surveys have taken place between June …


Microsatellite Analysis Of Population Structure In The Santa Ana Speckled Dace (Rhinicthys Osculus), Stacey A. Nerkowski Jun 2015

Microsatellite Analysis Of Population Structure In The Santa Ana Speckled Dace (Rhinicthys Osculus), Stacey A. Nerkowski

Electronic Theses, Projects, and Dissertations

Rhinichthys osculus, the Speckled Dace, is one of the most ubiquitous fish in western North America. Within the Southern California region, the local taxon is known as the Santa Ana Speckled Dace. The purpose of this study was to characterize and identify polymorphic microsatellite markers for R. osculus in which twenty-three were identified through Illumina pair-end sequencing. Seven of these loci were then used to examine the patterns of genetic variation and population structure that occurred within and among the watersheds in the Southern California. The study also examined the regional relationships among Southern California, Central California and Owen’s …


Socio-Economic Instability And The Scaling Of Energy Use With Population Size, John P. Delong, Oskar Burger Jun 2015

Socio-Economic Instability And The Scaling Of Energy Use With Population Size, John P. Delong, Oskar Burger

School of Biological Sciences: Faculty Publications

The size of the human population is relevant to the development of a sustainable world, yet the forces setting growth or declines in the human population are poorly understood. Generally, population growth rates depend on whether new individuals compete for the same energy (leading to Malthusian or density-dependent growth) or help to generate new energy (leading to exponential and super-exponential growth). It has been hypothesized that exponential and super-exponential growth in humans has resulted from carrying capacity, which is in part determined by energy availability, keeping pace with or exceeding the rate of population growth. We evaluated the relationship between …


Local Patterns In Host-Selection By Anemone Symbionts In Bocas Del Toro, Panama, Samantha Mercer May 2015

Local Patterns In Host-Selection By Anemone Symbionts In Bocas Del Toro, Panama, Samantha Mercer

Undergraduate Honors Theses

The associations made between many symbiotic cleaner shrimps and their host anemone species are influenced by local ecological factors, resulting in regional variations in symbiont-host preferences. These relationships are crucial parts of aquatic ecosystems, and as we face rapid global environmental change, understanding the local patterns of this host specificity will be essential to maintaining healthy marine environments. However, sea anemones, as well as their symbiotic relationships, from the Caribbean coasts of Panama have been poorly studied and are largely under-represented in the current literature. The purpose of this study is to identify the local host-selection patterns, specifically regarding host-size …


Distributional Expansion Of The Hispid Cotton Rat (Sigmodon Hispidus) Into Dawson County, Nebraska, Jennifer D. Frisch, Keith Geluso, Joseph T. Springer May 2015

Distributional Expansion Of The Hispid Cotton Rat (Sigmodon Hispidus) Into Dawson County, Nebraska, Jennifer D. Frisch, Keith Geluso, Joseph T. Springer

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

In the last century, the Hispid Cotton Rat (Sigmodon hispidus) has moved northward in central parts of the United States, reaching Nebraska in the late 1950s. Recent surveys demonstrate Hispid Cotton Rats inhabit counties across southern parts of Nebraska south of the Platte River. Herein, we report on captures of S. hispidus from a new county (Dawson County), its seasonal occurrence at our study site, and the first known record of the Hispid Cotton Rat north of channels of the Platte River. Our captures represent one of the northern-most records in Nebraska.


Fisheries Management Paper No 274 - Finfish Resources Of The Peel-Harvey Estuary - Harvest Strategy 2015-2020 (Version 1.0), Department Of Fisheries, Western Australia May 2015

Fisheries Management Paper No 274 - Finfish Resources Of The Peel-Harvey Estuary - Harvest Strategy 2015-2020 (Version 1.0), Department Of Fisheries, Western Australia

Fisheries Management Papers

WEST COAST ESTUARINE MANAGED FISHERY (AREA 2)

Harvest strategies for aquatic resources managed by the Western Australian Department of Fisheries (the Department) are formal documents prepared to support the decision-making processes required to ensure the management of these resources are consistent with the principles of Ecologically Sustainable Development (ESD). The objectives of ESD are reflected in the objects of the Fish Resources Management Act 1994 (FRMA), Section 3, and the draft Aquatic Resources Management Bill 2013 (ARMB), Clause 9, which will replace the FRMA once enacted.

The publication of these strategies is intended to make the decision-making considerations and processes …


Distribution Of The Egyptian Goose (Alopochen Aegyptiacus) In Northwestern Arkansas And In The United States Of America, Cameron Chesbro May 2015

Distribution Of The Egyptian Goose (Alopochen Aegyptiacus) In Northwestern Arkansas And In The United States Of America, Cameron Chesbro

Graduate Theses and Dissertations

The Egyptian Goose (Alopochen aegyptiacus) is an exotic member of the Anatidae that has been residing in northwestern Arkansas since the 1980s (Smith and James 2012). Following the discovery of Egyptian Geese in the area, not much attention has been given to the consequences of population increase. The Egyptian Goose has shown many diverse population growth patterns in areas where it has been introduced and started feral populations. The purpose of this study was to assess the current population size of the Egyptian Goose in northwestern Arkansas,and confirm successful breeding. The methods used in this study included conducting road surveys …


Genetic And Morphological Variation In Ecuadorian Astroblepid Catfishes, Katherine M. Lawry May 2015

Genetic And Morphological Variation In Ecuadorian Astroblepid Catfishes, Katherine M. Lawry

School of Natural Resources: Dissertations, Theses, and Student Research

The Andean ichthyofauna remains a poorly understood component of Neotropical biodiversity, and stands in stark contrast to the lowland ichthyofauna in terms of number of species and range of distribution. The Climate Variability Hypothesis (CVH) predicts rapid turnover of species along elevational gradients in tropical climates, but it remains unclear whether stream fishes follow this pattern. Astroblepid catfishes represent a distinctive assemblage of species that inhabit high elevation streams throughout the Andes from Panama to Bolivia, and constitute the only native fish family present in the Ecuadorian highland region. In this research, population samples of Astroblepids collected throughout Ecuador’s Napo …


Ecology And Management Of Superabundant Fish Populations, Nathaniel T. Stewart May 2015

Ecology And Management Of Superabundant Fish Populations, Nathaniel T. Stewart

School of Natural Resources: Dissertations, Theses, and Student Research

Fish population biomasses can reach extreme levels; we term these populations superabundant fish populations. Superabundant fish populations may negatively affect aquatic communities and anglers, necessitating the effective management of the superabundant fish populations. However, there are gaps in our understanding of these populations. The gaps in our understanding hamper our ability to predict effects on valuable sportfisheries and to effectively manage superabundant fish populations. The overall goal of my thesis research is to provide further insight into the ecology of superabundant fish populations and to provide information that will aid in their effective management. First, we described a new method …


Analysis Of The Diets Of The Northern Spotted Owl And Barred Owl, Valeria Briones Apr 2015

Analysis Of The Diets Of The Northern Spotted Owl And Barred Owl, Valeria Briones

Scholarly and Creative Works Conference (2015 - 2021)

The Northern Spotted Owl, a once thriving species is now a threatened species and on the verge of endangerment. The Barred Owl, a species native to the eastern United States over the past few centuries has expanded its range into that of the Northern Spotted Owl, causing a major threat to the Northern Spotted Owl Populations. This paper is a synthesis of the existing literature of the diets of the Northern Spotted Owl and Barred Owl individually as well as in areas in which they occur sympatrically. With this summary of literature, the reader can gain an understanding of the …


Some Agreement On Kin Selection And Eusociality?, David C. Queller, Stephen Rong, Xiaoyun Liao Apr 2015

Some Agreement On Kin Selection And Eusociality?, David C. Queller, Stephen Rong, Xiaoyun Liao

Biology Faculty Research

The authors of "Relatedness, Conflict, and the Evolution of Eusociality" respond to objections raised by Martin Nowak and Benjamin Allen.


Fauna Census Of Intertidal Cliffs, Mangapwani, Zanzibar, Emily Jankowski Apr 2015

Fauna Census Of Intertidal Cliffs, Mangapwani, Zanzibar, Emily Jankowski

Independent Study Project (ISP) Collection

Due to their extreme variations in condition over the course of a day, intertidal zones are challenging environments. Organisms that live there must be prepared to cope with both exposure and submersion, not to mention the temperature variations that accompany these conditions. The differing tolerances and adaptations of various organisms to these conditions generally cause patterns of vertical zonation to occur in the intertidal zone, especially when the shore is steep and rocky. Understanding the ecology of shore environments is important to future conservation and management efforts. This study was conducted on a beach in Mangapwani, Zanzibar at at 6˚ …


Marine Animalia Organism Diversity And Reef Condition On Two Reef Sites At Big Creek Beach And Boca Del Drago, Bocas Del Toro, Panamá, Bri Tiffany Apr 2015

Marine Animalia Organism Diversity And Reef Condition On Two Reef Sites At Big Creek Beach And Boca Del Drago, Bocas Del Toro, Panamá, Bri Tiffany

Independent Study Project (ISP) Collection

Ocean acidification, climate change, overfishing, and coastal development are endangering coral reefs across the globe. In Bocas del Toro, Panamá, coral reefs are especially threatened by the rapid growth in tourism and the subsequent anthropogenic effects caused by an increased human presence. To evaluate reef condition in this area, a study comparing percent coverage of live and dead coral as well as the diversity of marine Animalia organisms was conducted at one reef site in Big Creek beach and one reef site in Boca del Drago, Isla Colón, Bocas del Toro. It was predicted that dead coral cover would be …


Fisheries Management Paper No.273 - Blue Swimmer Crab Resource Of The Peel-Harvey Estuary Harvest Strategy, 2015-2020. Version 1.0, Department Of Fisheries, Western Australia Apr 2015

Fisheries Management Paper No.273 - Blue Swimmer Crab Resource Of The Peel-Harvey Estuary Harvest Strategy, 2015-2020. Version 1.0, Department Of Fisheries, Western Australia

Fisheries Management Papers

Harvest strategies for aquatic resources managed by the Western Australian Department of Fisheries (the Department) are formal documents prepared to support the decision-making processes required to ensure the management of these resources are consistent with the principles of Ecologically Sustainable Development (ESD). The objectives of ESD are reflected in the objects of the Fish Resources Management Act 1994 (FRMA), Section 3, and the draft Aquatic Resources Management Bill 2013 (ARMB), Clause 9, which will replace the FRMA once enacted.

The publication of these strategies is intended to make the decision-making considerations and processes for the management of specified aquatic resources …


The Behavioral Causes Of Reproductive Skew In Cooperatively Polygynandrous Acorn Woodpeckers (Melanerpes Formicivorus), Anna C. Brownson Apr 2015

The Behavioral Causes Of Reproductive Skew In Cooperatively Polygynandrous Acorn Woodpeckers (Melanerpes Formicivorus), Anna C. Brownson

Biological Sciences Theses & Dissertations

Reproductive skew, the degree to which reproduction is shared among same-sex individuals in a social group, is a pattern affected by ecological conditions, sociality, cooperation, and the inter- and intrasexual behavior of individuals in complex animal societies. Transactional and compromise skew models assume that high skew is the product of dominance hierarchies among cobreeders, yet this has rarely been tested. Both model types fail to incorporate the decisions of more than two individuals, generally overlooking the effect of female behavior on male reproductive success in multi-male groups, and are ineffective at predicting skew in larger groups characterized by more than …


A Comparison Of The Genetic Diversity Of The Class Ii Major Histocompatibility Complex In Ex Situ And In Situ Populations Of African Penguins (Spheniscus Demersus), Emily Willmer Apr 2015

A Comparison Of The Genetic Diversity Of The Class Ii Major Histocompatibility Complex In Ex Situ And In Situ Populations Of African Penguins (Spheniscus Demersus), Emily Willmer

Undergraduate Honors Thesis Projects

As an endangered species, the African penguin (Spheniscus demersus) is at risk of becoming extinct in the wild due to destruction of their coastal habitat and reduction in food availability. The development of a genetically diverse and healthy captive population is important in helping to conserve the species. The goal of this project was to determine the genetic diversity of the class II major histocompatibility complex (MHC) of a wild population of African penguins and compare it to the diversity of the captive population at Mystic Aquarium in Mystic, Connecticut that has previously been studied. We found that …


Concurrent Coevolution Of Intra-Organismal Cheaters And Resisters, S R. Levin, D A. Brock, David C. Queller, Joan E. Strassmann Apr 2015

Concurrent Coevolution Of Intra-Organismal Cheaters And Resisters, S R. Levin, D A. Brock, David C. Queller, Joan E. Strassmann

Biology Faculty Research

The evolution of multicellularity is a major transition that is not yet fully understood. Specifically, we do not know whether there are any mechanisms by which multicellularity can be maintained without a single-cell bottleneck or other relatedness-enhancing mechanisms. Under low relatedness, cheaters can evolve that benefit from the altruistic behaviour of others without themselves sacrificing. If these are obligate cheaters, incapable of cooperating, their spread can lead to the demise of multicellularity. One possibility, however, is that cooperators can evolve resistance to cheaters. We tested this idea in a facultatively multicellular social amoeba, Dictyostelium discoideum. This amoeba usually exists as …


Elevational Gradients In Β-Diversity Reflect Variation In The Strength Of Local Community Assembly Mechanisms Across Spatial Scales, J Sebastián Tello, Jonathan A. Myers, Manuel J. Macia, Alfredo F. Fuentes, Leslie Cayola, Gabriel Arellano, M Isabel Loza, Vania Torrez, Maritza Cornejo, Tatiana B. Miranda, Peter M. Jørgensen Mar 2015

Elevational Gradients In Β-Diversity Reflect Variation In The Strength Of Local Community Assembly Mechanisms Across Spatial Scales, J Sebastián Tello, Jonathan A. Myers, Manuel J. Macia, Alfredo F. Fuentes, Leslie Cayola, Gabriel Arellano, M Isabel Loza, Vania Torrez, Maritza Cornejo, Tatiana B. Miranda, Peter M. Jørgensen

Biology Faculty Research

Despite long-standing interest in elevational-diversity gradients, little is known about the processes that cause changes in the compositional variation of communities (β-diversity) across elevations. Recent studies have suggested that β-diversity gradients are driven by variation in species pools, rather than by variation in the strength of local community assembly mechanisms such as dispersal limitation, environmental filtering, or local biotic interactions. However, tests of this hypothesis have been limited to very small spatial scales that limit inferences about how the relative importance of assembly mechanisms may change across spatial scales. Here, we test the hypothesis that scale-dependent community assembly mechanisms shape …


An Individual-Based Model Of Chaparral Vegetation Response To Frequent Wildfire, Timothy Lucas, Dayna Mann, Reanna Dona Mar 2015

An Individual-Based Model Of Chaparral Vegetation Response To Frequent Wildfire, Timothy Lucas, Dayna Mann, Reanna Dona

Seaver College Research And Scholarly Achievement Symposium

In recent years, the Santa Monica Mountains (SMM) have been plagued by frequent wildfires which threaten the native chaparral species. Nonsprouting chaparral species are completely killed by a fire, but their seeds germinate in response to fire cues. Facultative sprouters both resprout after a wildfire and release seeds that germinate post-fire. This project is based on data collected since 1986 at a biological preserve adjacent to the Malibu campus of Pepperdine University with an average fire return interval of 7.5 years. We present a spatial model that simulates the growth, seed dispersal and resprouting behavior of individual shrubs that compete …