Life Sciences Commons^™

The Power Of Associative Learning And The Ontogeny Of Optimal Behaviour, Magnus Enquist, Johan Lind, Stefano Ghirlanda

Publications and Research

Behaving efficiently (optimally or near-optimally) is central to animals’ adaptation to their environment. Much evolutionary biology assumes, implicitly or explicitly, that optimal behavioural strategies are genetically inherited, yet the behaviour of many animals depends crucially on learning. The question of how learning contributes to optimal behaviour is largely open. Here we propose an associative learning model that can learn optimal behaviour in a wide variety of ecologically relevant circumstances. The model learns through chaining, a term introduced by Skinner to indicate learning of behaviour sequences by linking together shorter sequences or single behaviours. Our model formalizes the concept of conditioned …

Gruber Explores The Living Lights Of The Oceans., Aldemaro Romero Jr.

Publications and Research

The ocean waters are full of creatures that produce light, from microscopic organisms to sharks and marine turtles. Sometimes human vision is not prepared to detect it, but that does not mean such phenomena, known as bioluminescence and biofluorescence, are unimportant.

“There’s so many different ways in which life perceives light, and trying to get inside these animals, to get behind their eyes, is almost like walking in someone else’s shoes,” says Dr. David Gruber, an associate professor of biology at Baruch College in New York City. “It’s like being someone else for a day.”

Statistical Learning In Songbirds: From Self-Tutoring To Song Culture, Olga Fehér, Iva Ljubičić, Kenta Suzuki, Kazuo Okanoya, Ofer Tchernichovski

Publications and Research

At the onset of vocal development, both songbirds and humans produce variable vocal babbling with broadly distributed acoustic features. Over development, these vocalizations differentiate into the well-defined, categorical signals that characterize adult vocal behaviour. A broadly distributed signal is ideal for vocal exploration, that is, for matching vocal production to the statistics of the sensory input. The developmental transition to categorical signals is a gradual process during which the vocal output becomes differentiated and stable. But does it require categorical input?We trained juvenile zebra finches with playbacks of their own developing song, produced just a few moments earlier, updated continuously …

Sex And Seasonal Differences In Diet And Nutrient Intake In Verreaux's Sifakas (Propithecus Verreauxi), Flávia Koch, Joerg U. Ganzhorn, Jessica M. Rothman, Colin A. Chapman, Claudia Fichtel

Publications and Research

Fluctuations in food availability are a major challenge faced by primates living in seasonal climates. Variation in food availability can be especially challenging for females, because of the high energetic costs of reproduction. Therefore, females must adapt the particular demands of the different reproductive stages to the seasonal availability of resources. Madagascar has a highly seasonal climate, where food availability can be extremely variable. We investigated the seasonal changes in diet composition, nutrient and energy intake of female and male sifakas (Propithecus verreauxi) in a dry deciduous forest in western Madagascar. We examined how females adjust their diet to different …

Temporal Regularity Increases With Repertoire Complexity In The Australian Pied Butcherbird’S Song, Eathan Janney, Hollis Taylor, Constance Scharff, David Rothenberg, Lucas C. Parra, Ofer Tchernichovski

Publications and Research

Music maintains a characteristic balance between repetition and novelty. Here, we report a similar balance in singing performances of free-living Australian pied butcherbirds. Their songs include many phrase types. The more phrase types in a bird’s repertoire, the more diverse the singing performance can be. However, without sufficient temporal organization, avian listeners may find diverse singing performances difficult to perceive and memorize. We tested for a correlation between the complexity of song repertoire and the temporal regularity of singing performance. We found that different phrase types often share motifs (notes or stereotyped groups of notes). These shared motifs reappeared in …

A Species-Level Phylogeny Of Extant Snakes With Description Of A New Colubrid Subfamily And Genus, Alex Figueroa, Alexander D. Mckelvy, L. Lee Grismer, Charles D. Bell, Simon P. Lailvaux

Publications and Research

Background With over 3,500 species encompassing a diverse range of morphologies and ecologies, snakes make up 36% of squamate diversity. Despite several attempts at estimating higherlevel snake relationships and numerous assessments of generic- or species-level phylogenies, a large-scale species-level phylogeny solely focusing on snakes has not been completed. Here, we provide the largest-yet estimate of the snake tree of life using maximum likelihood on a supermatrix of 1745 taxa (1652 snake species + 7 outgroup taxa) and 9,523 base pairs from 10 loci (5 nuclear, 5 mitochondrial), including previously unsequenced genera (2) and species (61).

Results Increased taxon sampling resulted …

Physical Separation From The Mate Diminishes Male’S Attentiveness Towards Other Females: A Study In Monogamous Prairie Voles Microtus Ochrogaster, Christine J. Delevan, Natalia A. Rodriguez, Karine M. Legzim, Fayeza Aliou, Jamie T. Parker, Maryam Bashad

Publications and Research

We tested whether continuous cohabitation in monogamous voles affects the mated male’s attentiveness to his breeding partner versus another female. Each male was housed in a 3-chamber apparatus with a Focal female (FF) and a Control female (CF) for 13 days then placed in a T-maze to assess his attentiveness to and memory of those females. The Distal male remained physically separated from both females, but received their distal cues. The Separate male cohabited with the FF for 3 days then remained physically separated from both females. The Disrupt male’s continuous cohabitation with the FF was disrupted by having him …

Molecular Tracking Of Individual Host Use In The Shiny Cowbird – A Generalist Brood Parasite, Ma Alicia De La Colina, Mark E. Hauber, Bill M. Strausberger, Juan Carlos Reboreda, Bettina Mahler

Publications and Research

Generalist parasites exploit multiple host species at the population level, but the individual parasite’s strategy may be either itself a generalist or a specialist pattern of host species use. Here, we studied the relationship between host availability and host use in the individual parasitism patterns of the Shiny Cowbird Molothrus bonariensis, a generalist avian obligate brood parasite that parasitizes an extreme range of hosts. Using five microsatellite markers and an 1120-bp fragment of the mtDNA control region, we reconstructed full-sibling groups from 359 cowbird eggs and chicks found in nests of the two most frequent hosts in our study area, …

Finding The Beat: From Socially Coordinated Vocalizations In Songbirds To Rhythmic Entrainment In Humans, Jonathan I. Benichov, Eitan Globerson, Ofer Tchernichovski

Publications and Research

Humans and oscine songbirds share the rare capacity for vocal learning. Songbirds have the ability to acquire songs and calls of various rhythms through imitation. In several species, birds can even coordinate the timing of their vocalizations with other individuals in duets that are synchronized with millisecond-accuracy. It is not known, however, if songbirds can perceive rhythms holistically nor if they are capable of spontaneous entrainment to complex rhythms, in a manner similar to humans. Here we review emerging evidence from studies of rhythm generation and vocal coordination across songbirds and humans. In particular, recently developed experimental methods have revealed …

Dynamic Egg Color Mimicry, Daniel Hanley, Michael Sulc, Patricia L. R. Brennan, Mark E. Hauber, Tomas Grim, Marcel Honza

Publications and Research

Evolutionary hypotheses regarding the function of eggshell phenotypes, from solar protection through mimicry, have implicitly assumed that eggshell appearance remains static throughout the laying and incubation periods. However, recent research demonstrates that egg coloration changes over relatively short, biologically relevant timescales. Here, we provide the first evidence that such changes impact brood parasite–host eggshell color mimicry during the incubation stage. First, we use long-term data to establish how rapidly the Acrocephalus arundinaceus Linnaeus (great reed warbler) responded to natural parasitic eggs laid by the Cuculus canorus Linnaeus (common cuckoo). Most hosts rejected parasitic eggs just prior to clutch completion, but …

Shakespeare's Blush, Or "The Animal" In Othello, Steven Swarbrick

Publications and Research

This essay examines how the rhetoric of animalization in Shakespeare’s Othello compels us to think early modern categories of race in connection with early modern discourses of “human” versus “animal.” Beginning with Shakespeare’s representation of Iago, I suggest that it is the potential for sameness conditioned by Iago’s counterfactual statement (“Were I the Moor, I would not by Iago”) that is most significant about his relation to Othello. From there I consider the overlap between the play’s representations of animality and black skin. Read in the context of Jacques Derrida’s reflections on animals, I consider the deconstructive value of linking …

Diversity-Dependent Cladogenesis Throughout Western Mexico: Evolutionary Biogeography Of Rattlesnakes (Viperidae: Crotalinae: Crotalus And Sistrurus), Christopher Blair, Santiago Sánchez-Ramírez

Publications and Research

Rattlesnakes (Crotalus and Sistrurus) represent a radiation of approximately 42 species distributed throughout the New World from southern Canada to Argentina. Interest in this enigmatic group of snakes continues to accrue due, in part, to their ecomorphological diversity, contributions to global envenomations, and potential medicinal importance. Although the group has garnered substantial attention from systematists and evolutionary biologists for decades, little is still known regarding patterns of lineage diversification. In addition, few studies have statistically quantified broad-scale biogeographic patterns in rattlesnakes to ascertain how dispersal occurred throughout the New World, particularly among the different major biomes of the …

Can Colour Vision Re-Evolve? Variation In The X-Linked Opsin Locus Of Cathemeral Azara’S Owl Monkeys (Aotus Azarae Azarae), N. I. Mundy, N. C. Morningstar, Andrea L. Baden, E. Fernandez-Duque, V. M. Davalos, B. J. Bradley

Publications and Research

Background: Do evolutionary specializations lead to evolutionary constraint? This appears plausible, particularly when specialization leads to loss of complex adaptations. In the owl monkey lineage, nocturnality clearly arose from a diurnal ancestor. This behavioural shift was accompanied by morphological changes in the eye and orbit and complete loss of colour vision via missense mutations in the gene encoding the short-wave sensitive visual pigment (SWS opsin). Interestingly, at least one subspecies of owl monkey, Azara’s owl monkey (Aotus azarae azarae), has regained activity in daylight. Given that all primate species that are active in daylight, including primarily diurnal species and species …

Eggshell Pigment Composition Covaries With Phylogeny, Kaat Brulez, Ivan Miksik, Christopher R. Cooney, Mark E. Hauber, Paul George Lovell, Golo Maurer, Steven J. Portugal, Douglas Russell, Silas James Reynolds, Phillip Cassey

Publications and Research

No single hypothesis is likely to explain the diversity in eggshell coloration and patterning across birds, suggesting that eggshell appearance is most likely to have evolved to fulfill many nonexclusive functions. By controlling for nonindependent phylogenetic associations between related species, we describe this diversity using museum eggshells of 71 British breeding passerine species to examine how eggshell pigment composition and concentrations vary with phylogeny and with life-history and nesting ecology traits. Across species, concentrations of biliverdin and protoporphyrin, the two main pigments found in eggshells, were strongly and positively correlated, and both pigments strongly covaried with phylogenetic relatedness. Controlling for …