About

Andrew Kahrl is an Associate Professor in the Department of American Studies and History at the University of Virginia. His academic role involves engaging with political and social thought, contributing to the university's broader educational mission. As a faculty member, he is involved in teaching and research that explore themes related to social and political issues, although specific details about his research focus or key contributions are not provided on the page. His professional profile indicates a commitment to academic excellence and participation in university programs, but no further biographical information is available from the provided text.

Research topics

• Evolutionary biology
• Biology
• Ecology
• Zoology
• Botany
• Genetics

Selected publications

• Review for "Sperm storage causes sperm senescence in human and non-human animals"

  2026-01-09

  peer-review1st authorCorresponding
  PublisherDOI

• The evolution of testis architecture and sperm size in <i>Anolis</i> lizards

  Biological Journal of the Linnean Society · 2025-04-01

  article1st authorCorresponding

  Abstract The major function of the testes is the production of sperm cells. Across species there are dramatic differences in sperm morphology, and this variation may result from variation in the internal structure of the testis. Yet, the extent to which testis anatomy is associated with sperm size remains unclear. In this study, we used 20 species of Anolis lizards to examine interspecific relationships between testis architecture and sperm component lengths, as well as testis architecture and a proxy for copulation rate (hemipenis muscle damage), using both phylogenetic and regular linear models. Results of our evolutionary analysis indicate that testis and sperm components have high phylogenetic signal. Further, testis architecture and sperm component length, and the variance in these traits, are not associated with one another using phylogenetic linear models, although non-phylogenetic analyses suggest that larger testes produce sperm with longer flagella. Our interpretation of these conflicting models is that the strong phylogenetic signal of these traits may mask significant functional and developmental relationships in phylogenetic models that regular linear models reveal. This suggests that these traits are not experiencing selection that would cause these traits to covary in a different pattern than their phylogenetic relationships; instead, in this group they are likely evolving together neutrally.

  PublisherDOI

• The landscape of natural selection during early population establishment in an invasive lizard

  Evolution · 2025-09-13

  article

  Populations during early stages of establishment are sensitive to forms of demographic regulation coinciding with rapid growth, which may also coincide with specific patterns of natural selection due to demographic variation. Understanding how selection varies during the establishment of new populations, however, is complicated by the constraint of knowing the precise age of a population as it grows over time. To address this, we established six brown anole (Anolis sagrei) populations on spoil islands in Florida and manipulated initial sex ratios to understand how natural selection is influenced by the demographic composition of founding populations. We found that initial sex ratios of founding populations led to age-specific patterns of natural selection. Juveniles experienced stronger selection in populations that began with a female-biased sex ratio, and the strength of natural selection on juvenile size strengthened with increasing population density. We also found substantial variation in selection, suggesting that the relationship between phenotypes and fitness across early generations of a population is not consistent over time. As a result, variation in natural selection driven by demographic aspects within populations may provide opportunities for rapid population growth and novel evolutionary trajectories during the earliest stages of establishment.

  PublisherDOI

• Review for "Sperm storage causes sperm senescence in human and non-human animals"

  2025-09-16

  peer-review1st authorCorresponding
  PublisherDOI

• Relationships between Pre- and Postcopulatory Sexually Selected Traits in Green Frogs ( <i>Lithobates clamitans</i> )

  Integrative Organismal Biology · 2025-01-01

  articleOpen accessSenior author

  Synopsis Sexual selection is thought to be a primary driver of trait evolution. The expression of traits that improve mate acquisition or fertilization success may be linked in organisms that experience intense sexual selection as they must invest sufficient energy into many different sexual traits in order to reproduce. Two prevailing models—the phenotype-linked fertility hypothesis and the trade-off hypothesis—describe potential positive or negative correlations, respectively, between pre- and postcopulatory traits. We examined the interaction between precopulatory traits (belly coloration and forearm size) and postcopulatory traits (sperm morphology, sperm velocity, and sperm count) in male Green Frogs (Lithobates clamitans). We found multiple positive and negative correlations between pre- and postcopulatory sexual traits. Interestingly, belly saturation and hue, which are precopulatory traits, were negatively correlated with sperm count and sperm length, suggesting that the expression of these traits is constrained by energetic resources, fitting the trade-off hypothesis. However, male forearm size was positively correlated with both sperm count and sperm velocity but negatively correlated with sperm length. These results suggest that males must make complex investments in suites of sexual traits to maximize fitness in the face of energetic trade-offs.

  PublisherOA PDFDOI

• Correction to: The landscape of natural selection during early population establishment in an invasive lizard

  Evolution · 2025-11-20

  erratum

  International audience

  PublisherDOI

• Fertilization Modes Across Animals

  Elsevier eBooks · 2025-06-26

  book-chapter1st authorCorresponding
  PublisherDOI

• Parental age effects on offspring fitness in a wild population of a short-lived reptile

  Journal of Evolutionary Biology · 2025-10-17

  article

  As organisms age, the fitness of the offspring they produce can decline, which is often attributed to parental senescence. However, few studies have tested for effects of parental age on offspring fitness in wild populations or in short-lived vertebrates, and only recently have studies begun to examine such effects in male and female offspring independently. Here, we use five generations of mark-recapture and genetic parentage data from an island population of a short-lived lizard, the brown anole (Anolis sagrei), to test for effects of maternal and paternal age on the survival to adulthood, first-year reproductive success, longevity, and lifetime fitness of their offspring. When comparing parents of different ages within the same offspring cohort, survival to adulthood increased with paternal age in sons, but we found no effects of maternal or paternal age on any component of fitness in daughters and no evidence that parental age effects differed based on the sex of the parent or the offspring. When considering repeated measures of individual parents sampled at multiple ages, we found that first-year reproductive success of sons decreased with paternal age, but longevity of sons increased with maternal age. However, when pooling sons and daughters, we found no overall effects of parental age on any component of offspring fitness, and little evidence that parental age effects differed between sons and daughters. Our study adds to the growing literature suggesting that negative effects of parental age on offspring fitness may not be as prevalent as once thought, particularly in wild populations.

  PublisherDOI

• Resource-dependent investment in male sexual traits in a viviparous fish

  Behavioral Ecology · 2022-06-23 · 10 citations

  articleOpen access

  Abstract Exaggerated and conspicuous sexually selected traits are often costly to produce and maintain. Costly traits are expected to show resource-dependent expression, since limited resources prevent animals from investing maximally in multiple traits simultaneously. However, there may be critical periods during an individual’s life where the expression of traits is altered if resources are limited. Moreover, costly sexual traits may arise from sexual selection acting both before (pre-copulatory) and after mating (post-copulatory). Gaining a robust understanding of resource-dependent trait expression therefore requires an approach that examines both episodes of sexual selection after resource limitation during different times in an individual’s life. Yet few studies have taken such an approach. Here, we examine how resource restriction influences a set of pre- and post-copulatory traits in male pygmy halfbeaks (Dermogenys collettei), which invest in sexual ornaments and routinely engage in male–male contests and sperm competition. Critically, we examined responses in males when resources were restricted during development and after reaching sexual maturity. Both pre- and post-copulatory traits are resource-dependent in male halfbeaks. Body size, beak size, courtship behavior, and testes size were reduced by diet restriction, while, unexpectedly, the restricted-diet group had a larger area of red color on the beak and fins after diet treatment. These patterns were generally consistent when resources were restricted during development and after reaching sexual maturity. The study reinforces the role of resource acquisition in maintaining variation among sexual traits.

  PublisherOA PDFDOI

• Fertilization mode differentially impacts the evolution of vertebrate sperm components

  Nature Communications · 2022-11-10 · 30 citations

  articleOpen access1st authorCorresponding

  Environmental change frequently drives morphological diversification, including at the cellular level. Transitions in the environment where fertilization occurs (i.e., fertilization mode) are hypothesized to be a driver of the extreme diversity in sperm morphology observed in animals. Yet how fertilization mode impacts the evolution of sperm components-head, midpiece, and flagellum-each with different functional roles that must act as an integrated unit remains unclear. Here, we test this hypothesis by examining the evolution of sperm component lengths across 1103 species of vertebrates varying in fertilization mode (external vs. internal fertilization). Sperm component length is explained in part by fertilization mode across vertebrates, but how fertilization mode influences sperm evolution varies among sperm components and vertebrate clades. We also identify evolutionary responses not influenced by fertilization mode: midpieces evolve rapidly in both external and internal fertilizers. Fertilization mode thus influences vertebrate sperm evolution through complex component- and clade-specific evolutionary responses.

  PublisherOA PDFDOI

Frequent coauthors

• Robert M. Cox

  University of Virginia

  16 shared

• Amélie Fargevieille

  12 shared

• Daniel A. Warner

  Auburn University

  10 shared

• Aaron M. Reedy

  Purdue University System

  10 shared

• John L. Fitzpatrick

  Stockholm University

  8 shared

• Timothy S. Mitchell

  University of Minnesota

  7 shared

• Phillip R. Pearson

  University of Canberra

  7 shared

• David M. Delaney

  Iowa State University

  6 shared

Education

• Doctor of Philosophy, Biology

  University of Virginia

  2017

• Bachelors of Arts, Biology

  Oberlin College

  2009