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E P Martins

Publications and source records attributed to E P Martins.

4 recordsLinked to original sources
PubMed2006

Individual, sexual, seasonal, and temporal variation in the amount of sagebrush lizard scent marks.

Although many animals deposit scent marks, previous studies have focused almost entirely on rodents or on the chemical structure of the signal. Here, we study the quantity and temporal pattern of chemical deposition by the territorial sagebrush lizard Sceloporus graciosus, measuring both femoral pore and fecal deposits. Specifically, we tested whether variation in deposition is a good cue of individual and sexual identity and/or whether it is more closely associated with body size and reproductive state, indicators of physiological condition. The results support the latter hypothesis. We found that although the amount of fluid deposited on a single perch (rarely quantified in mammals) carries little information on individual or sexual identity, it reflects the physiological condition and reproductive state of individual lizards and is replenished on a roughly weekly cycle, potentially providing additional information on the producer's activity level. The amount of deposition may thus provide important information to chemical receivers making mate choice and territorial defense decisions. The results further suggest that seasonal increases in gland production allow lizards to mark more sites rather than to influence the quality of the signal on a single perch.

Animals↗
PubMed1995

Phylogenies and comparative data, a microevolutionary perspective.

As species evolve along a phylogenetic tree, their phenotypes diverge. We expect closely related species to retain some phenotypic similarities owing to their shared evolutionary histories. The degree of similarity depends both on the phylogeny and on the detailed evolutionary changes that accumulate each generation. In this study, I review a general framework that can be used to translate between macroevolutionary patterns and the underlying microevolutionary process by comparing the observed relationships among measured species phenotypes and the expected relationship structure due to the phylogeny and underlying models of phenotypic evolution. I then show how the framework can be used to compare methods used (1) to reconstruct phylogenies, (2) to correct comparative data for phylogenetic non-independence, and (3) to infer details of the microevolutionary process from interspecific data and a phylogeny. Use of this framework and a microevolutionary perspective on the analysis of interspecific data opens up new fields of inquiry and many new uses for phylogenies and comparative data.

Animals↗
PubMedDate not supplied

Random sampling of constrained phylogenies: conducting phylogenetic analyses when the phylogeny is partially known.

Statistical randomization tests in evolutionary biology often require a set of random, computer-generated trees. For example, earlier studies have shown how large numbers of computer-generated trees can be used to conduct phylogenetic comparative analyses even when the phylogeny is uncertain or unknown. These methods were limited, however, in that (in the absence of molecular sequence or other data) they allowed users to assume that no phylogenetic information was available or that all possible trees were known. Intermediate situations where only a taxonomy or other limited phylogenetic information (e.g., polytomies) are available are technically more difficult. The current study describes a procedure for generating random samples of phylogenies while incorporating limited phylogenetic information (e.g., four taxa belong together in a subclade). The procedure can be used to conduct comparative analyses when the phylogeny is only partially resolved or can be used in other randomization tests in which large numbers of possible phylogenies are needed.

Biometry↗