Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 7 of 7
Full-Text Articles in Life Sciences
The Dynamics Of Dominance: Open Questions, Challenges And Solutions, Eli D. Strauss, Daizaburo Shizuka
The Dynamics Of Dominance: Open Questions, Challenges And Solutions, Eli D. Strauss, Daizaburo Shizuka
School of Biological Sciences: Faculty Publications
Although social hierarchies are recognized as dynamic systems, they are typically treated as static entities for practical reasons. Here, we ask what we can learn from a dynamical view of dominance, and provide a research agenda for the next decades. We identify five broad questions at the individual, dyadic and group levels, exploring the causes and consequences of individual changes in rank, the dynamics underlying dyadic dominance relationships, and the origins and impacts of social instability. Although challenges remain, we propose avenues for overcoming them. We suggest distinguishing between different types of social mobility to provide conceptual clarity about hierarchy …
Sex Role Similarity And Sexual Selection Predict Male And Female Song Elaboration And Dimorphism In Fairy-Wrens, Karan J. Odom, Kristal E. Cain, Michelle L. Hall, Naomi E. Langmore, Raoul A. Mulder, Sonia Kleindorfer, Jordan Karubian, Lyanne Brouwer, Emma I. Greig, Christine Evans, Allison E. Johnson, Kimberley K.-A. Meyers, Marcelo Araya-Salas, Michael S. Webster, Erik D. Enbody, John Anthony Jones, Jenélle L. Dowling, Ana V. Leitão
Sex Role Similarity And Sexual Selection Predict Male And Female Song Elaboration And Dimorphism In Fairy-Wrens, Karan J. Odom, Kristal E. Cain, Michelle L. Hall, Naomi E. Langmore, Raoul A. Mulder, Sonia Kleindorfer, Jordan Karubian, Lyanne Brouwer, Emma I. Greig, Christine Evans, Allison E. Johnson, Kimberley K.-A. Meyers, Marcelo Araya-Salas, Michael S. Webster, Erik D. Enbody, John Anthony Jones, Jenélle L. Dowling, Ana V. Leitão
School of Biological Sciences: Faculty Publications
Historically, bird song complexity was thought to evolve primarily through sexual selection on males; yet, in many species, both sexes sing and selection pressure on both sexes may be broader. Previous research suggests competition for mates and resources during short, synchronous breeding seasons leads to more elaborate male songs at high, temperate latitudes. Furthermore, we expect male–female song structure and elaboration to be more similar at lower, tropical latitudes, where longer breeding seasons and year-round territoriality yield similar social selection pressures in both sexes. However, studies seldom take both types of selective pressures and sexes into account. We examined song …
Phenotypically Plastic Responses To Predation Risk Are Temperature Dependent, Thomas M. Luhring, Janna M. Vavra, Clayton E. Cressler, John Delong
Phenotypically Plastic Responses To Predation Risk Are Temperature Dependent, Thomas M. Luhring, Janna M. Vavra, Clayton E. Cressler, John Delong
School of Biological Sciences: Faculty Publications
Predicting how organisms respond to climate change requires that we understand the temperature dependence of fitness in relevant ecological contexts (e.g., with or without predation risk). Predation risk often induces changes to life history traits that are themselves temperature dependent. We explore how perceived predation risk and temperature interact to determine fitness (indicated by the intrinsic rate of increase, r) through changes to its underlying components (net reproductive rate, generation time, and survival) in Daphnia magna. We exposed Daphnia to predation cues from dragonfly naiads early, late, or throughout their ontogeny. Predation risk increased r differentially across temperatures …
Testing The Terminal Investment Hypothesis In California Oaks, Walter D. Koenig, Johannes M.H. Knops, William J. Carmen, Mario B. Pesendorfer
Testing The Terminal Investment Hypothesis In California Oaks, Walter D. Koenig, Johannes M.H. Knops, William J. Carmen, Mario B. Pesendorfer
School of Biological Sciences: Faculty Publications
The terminal investment hypothesis—which proposes that reproductive investment should increase with age-related declines in reproductive value—has garnered support in a range of animal species but has not been previously examined in long-lived plants, such as trees. We tested this hypothesis by comparing relative acorn production and radial growth among 1,0001 mature individuals of eight species of California oaks (genus Quercus) followed for up to 37 years, during which time 70 trees died apparently natural deaths. We found no significant differences in the radial growth, acorn production, or index of reproductive effort, taking into consideration both growth and reproduction among dying …
Effects Of Endogenous Steroid Hormone Levels On Annual Survival In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown, Samrrah A. Raouf, Linda C. Smith, John C. Wingfield
Effects Of Endogenous Steroid Hormone Levels On Annual Survival In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown, Samrrah A. Raouf, Linda C. Smith, John C. Wingfield
School of Biological Sciences: Faculty Publications
The hormone corticosterone is an important part of animals’ response to environmental stress, modulating short-term adaptive changes in behavior and physiology. The hormone testosterone is also critical, especially for males, in regulating the expression of sexual behavior and parental care. These hormones can have costly consequences, however, and within populations individuals show variation in endogenous levels of both corticosterone and testosterone. We studied how annual survival varied as a function of natural levels of these hormones in colonially breeding Cliff swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, USA, in 2000–2003. We sampled hormone levels of birds caught at colonies …
Testis Size Increases With Colony Size In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown
Testis Size Increases With Colony Size In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown
School of Biological Sciences: Faculty Publications
By using a sample of more than 800 male cliff swallows (Petrochelidon pyrrhonota) that died during a rare climatic event in our Nebraska study area in 1996, we investigated how testis size was related to body size, age, parasite load, a bird’s past colony-size history, and spleen size. Testis volume in-creased with body size. After correcting for body size, testis volume was lowest for birds age 1 and 2 years but did not vary with age for males 3 years old or more. Birds occupying parasite-free (fumigated) colonies had significantly larger testes than did birds at non-fumigated sites. …
Multistate Estimates Of Survival And Movement In Relation To Colony Size In The Sociable Weaver, Charles R. Brown, Rita Covas, Mark D. Anderson, Mary Bomberger Brown
Multistate Estimates Of Survival And Movement In Relation To Colony Size In The Sociable Weaver, Charles R. Brown, Rita Covas, Mark D. Anderson, Mary Bomberger Brown
School of Biological Sciences: Faculty Publications
We estimated survival and movement probabilities in relation to breeding-colony size in the sociable weaver (Philetairus socius) by using multistate statistical methods, in which survival and movement to time t + 1 is conditional on an individual’s colony size at time t. The sociable weaver is a colonial, cooperatively breeding species that builds a massive communal nest, with colony size ranging from fewer than 20 to more than 500 individuals in some areas. We conducted an 8-year capture/mark/re-capture study of sociable weavers near Kimberley, South Africa. By comparing the fit of different multistate models to our data, we found evidence …