Alexa Corinne Pollock

All Publications

• Recurrent evolution of small body size and loss of the sword ornament in Northern swordtail fish. Evolution; international journal of organic evolution Preising, G. A., Gunn, T., Baczenas, J. J., Powell, D. L., Dodge, T. O., Sewell, S. T., Pollock, A., Machin Kairuz, J. A., Savage, M., Lu, Y., Fitschen-Brown, M., Meyer, A., Schartl, M., Cummings, M., Thakur, S., Inman, C. M., Ríos-Cardenas, O., Morris, M., Tobler, M., Schumer, M. 2024

  Abstract

  Across the tree of life, species have repeatedly evolved similar phenotypes. While well-studied for ecological traits, there is also evidence for recurrent evolution of sexually selected traits. Swordtail fish (Xiphophorus) are a classic model system for studying sexual selection, and female Xiphophorus exhibit strong mate preferences for large male body size and a range of sexually dimorphic ornaments. Interestingly, sexually selected traits have also been lost multiple times in the genus. However, there has been uncertainty over the number of losses of ornamentation and large body size because phylogenetic relationships between species in this group have historically been controversial, partially due to prevalent gene flow. Here, we use whole-genome sequencing approaches to re-examine phylogenetic relationships within a Xiphophorus clade that varies in the presence and absence of sexually selected traits. Using wild-caught individuals, we determine the phylogenetic placement of a small, unornamented species, X. continens, confirming an additional loss of ornamentation and large body size in the clade. With these revised phylogenetic relationships, we analyze evidence for coevolution between body size and other sexually selected traits using phylogenetic comparative methods. These results provide insights into the evolutionary pressures driving the recurrent loss of suites of sexually selected traits.

  View details for DOI 10.1093/evolut/qpae124

  View details for PubMedID 39252584

• Albino Xenopus laevis tadpoles prefer dark environments compared to wild type. microPublication biology Adebogun, G. T., Bachmann, A. E., Callan, A. A., Khan, U., Lewis, A. R., Pollock, A. C., Alfonso, S. A., Arango Sumano, D., Bhatt, D. A., Cullen, A. B., Hajian, C. M., Huang, W., Jaeger, E. L., Li, E., Maske, A. K., Offenberg, E. G., Ta, V., Whiting, W. W., McKinney, J. E., Butler, J., O'Connell, L. A. 2023; 2023

  Abstract

  Tadpoles display preferences for different environments but the sensory modalities that govern these choices are not well understood. Here, we examined light preferences and associated sensory mechanisms of albino and wild-type Xenopus laevis tadpoles. We found that albino tadpoles spent more time in darker environments compared to the wild type, although they showed no differences in overall activity. This preference persisted when the tadpoles had their optic nerve severed or pineal glands removed, suggesting these sensory systems alone are not necessary for phototaxis. These experiments were conducted by an undergraduate laboratory course, highlighting how X. laevis tadpole behavior assays in a classroom setting can reveal new insights into animal behavior.

  View details for DOI 10.17912/micropub.biology.000750

  View details for PubMedID 36824381

  View details for PubMedCentralID PMC9941856

• Argentine ant extract induces an osm-9 dependent chemotaxis response in C. elegans. microPublication biology Alfonso, S. A., Arango Sumano, D., Bhatt, D. A., Cullen, A. B., Hajian, C. M., Huang, W., Jaeger, E. L., Li, E., Maske, A. K., Offenberg, E. G., Ta, V., Whiting, W. W., Adebogun, G. T., Bachmann, A. E., Callan, A. A., Khan, U., Lewis, A. R., Pollock, A. C., Ramirez, D., Bradon, N., Fiocca, K., Cote, L. E., Sallee, M. D., McKinney, J., O'Connell, L. A. 2023; 2023

  Abstract

  Many ant species are equipped with chemical defenses, although how these compounds impact nervous system function is unclear. Here, we examined the utility of Caenorhabditis elegans chemotaxis assays for investigating how ant chemical defense compounds are detected by heterospecific nervous systems. We found that C. elegans respond to extracts from the invasive Argentine Ant ( Linepithema humile ) and the osm-9 ion channel is required for this response. Divergent strains varied in their response to L. humile extracts, suggesting genetic variation underlying chemotactic responses. These experiments were conducted by an undergraduate laboratory course, highlighting how C. elegans chemotaxis assays in a classroom setting can provide genuine research experiences and reveal new insights into interspecies interactions.

  View details for DOI 10.17912/micropub.biology.000745

  View details for PubMedID 37008729