Population Biology Commons^™

Changes In The Diet And Body Size Of A Small Herbivorous Mammal (Hispid Cotton Rat, Sigmodon Hispidus) Following The Late Pleistocene Megafauna Extinction, Catalina P. Tomé, Emma A. Elliott Smith, S. Kathleen Lyons, Seth D. Newsome, Felisa A. Smith

School of Biological Sciences: Faculty Publications

The catastrophic loss of large-bodied mammals during the terminal Pleistocene likely led to cascading effects within communities. While the extinction of the top consumers probably expanded the resources available to survivors of all body sizes, little work has focused on the responses of the smallest mammals. Here, we use a detailed fossil record from the southwestern United States to examine the response of the hispid cotton rat Sigmodon hispidus to biodiversity loss and climatic change over the late Quaternary. In particular, we focus on changes in diet and body size. We characterize diet through carbon (δ¹³C) and nitrogen …

Body Size Downgrading Of Mammals Over The Late Quaternary, Felisa A. Smith, Rosemary E. Elliott Smith, S. Kathleen Lyons, Jonathan L. Payne

School of Biological Sciences: Faculty Publications

Since the late Pleistocene, large-bodied mammals have been extirpated from much of Earth. Although all habitable continents once harbored giant mammals, the few remaining species are largely confined to Africa. This decline is coincident with the global expansion of hominins over the late Quaternary. Here, we quantify mammalian extinction selectivity, continental body size distributions, and taxonomic diversity over five time periods spanning the past 125,000 years and stretching approximately 200 years into the future. We demonstrate that size-selective extinction was already under way in the oldest interval and occurred on all continents, within all trophic modes, and across all time …

Biotic Interchange Has Structured Western Hemisphere Mammal Communities, Danielle Fraser, S. Kathleen Lyons

School of Biological Sciences: Faculty Publications

Aim.— Many hypotheses posit that species-rich tropical communities are dominated by speciesspecies interactions, apparent as competitive exclusion or character displacement, whereas species-poor temperate communities are dominated by species-environment interactions. Recent studies demonstrate a strong influence of macroevolutionary and biogeographic factors. We simultaneously test for the effects of species interactions, climate, and biotic interchange on Western Hemisphere mammal communities using a phylogenetic and functional diversity approach.

Location.— Western Hemisphere.

Time period.— Modern

Major taxa studied.— Mammalia

Methods.— Using Western Hemisphere mammal distributional and body mass data, we calculate body mass dispersion, phylogenetic diversity (Net Relatedness Index), and assemblage-averaged rates of co-occurrence …

The Maintenance Of Phenotypic Divergence Through Sexual Selection: An Experimental Study In Barn Swallows Hirundo Rustica, Rebecca Safran, Yoni Vortman, Brittany R. Jenkins, Joanna K. Hubbard, Matt Wilkins, Rachel J. Bradley, Arnon Lotem

School of Biological Sciences: Faculty Publications

Previous studies have shown that sexual signals can rapidly diverge among closely related species. However, we lack experimental studies to demonstrate that differences in trait-associated reproductive performance maintain sexual trait differences between closely related populations, in support for a role of sexual selection in speciation. Populations of Northern Hemisphere distributed barn swallows Hirundo rustica are closely related, yet differ in two plumage-based traits: ventral color and length of the outermost tail feathers (streamers). Here we provide experimental evidence that manipulations of these traits result in different reproductive consequences in two subspecies of barn swallow: (H. r. erythrogaster in North …

Tiger Salamanders Disappearing In Region, Dennis M. Ferraro

School of Biological Sciences: Faculty Publications

"Where have all the salamanders gone?" 'This is a question I have been increasingly asked over the past five to six years from area residents. It seems we are observing a dramatic population decline of the western barred tiger salamander in parts of Southeast Nebraska. The western barred tiger salamander (Ambystoma mavortium) is one of only two salamanders in Nebraska. Over the past two years, none have been found in southeast Nebraska.

Salamanders, like all amphibians, are excellent indicator species. In many cases they act like the iconic canary in the mine shaft, telling us when to run …

Spatiotemporal Variation In Flow-Dependent Recruitment Of Long-Lived Riverine Fish: Model Development And Evaluation, Daisuke Goto, Martin J. Hamel, Jeremy J. Hammen, Mathew L. Rugg, Mark A. Pegg, Valery E. Forbes

School of Biological Sciences: Faculty Publications

Abstract Natural flow regimes can play a major role as an overarching ecosystem driver in reproduction and recruitment of riverine fishes. Human needs for freshwater however have altered hydrology of many riverine systems worldwide, threatening fish population sustainability. To understand and predict how spatiotemporal dynamics of flow regimes influence reproductive and recruitment variability, and ultimately population sustainability of shovelnose sturgeon (Scaphirhynchus platorynchus), we develop a spatially explicit (1D) individual-based population model that mechanistically (via energetics-based processes) simulates daily activities (dispersal, spawning, foraging, growth, and survival). With field observations of sturgeon and habitat conditions in a major tributary of …

Across-Year Social Stability Shapes Network Structure In Wintering Migrant Sparrows, Daizaburo Shizuka, Alexis S. Chaine, Jennifer Anderson, Oscar Johnson, Inger Marie Laursen, Bruce E. Lyon

School of Biological Sciences: Faculty Publications

Migratory birds often form flocks on their wintering grounds, but important details of social structure such as the patterns of association between individuals are virtually unknown. We analysed networks of co-membership in short-term flocks for wintering golden-crowned sparrows (Zonotrichia atricapilla) across three years and discovered social complexity unsuspected for migratory songbirds. The population was consistently clustered into distinct social communities within a relatively small area (~ 7 ha). Birds returned to the same community across years, with mortality and recruitment leading to some degree of turnover in membership. These spatiotemporal patterns were explained by the combination of space …