Microevolutionary studies often find that complex quantitative characters are highly evolvable and adapted to the local environment, while macroevolutionary studies often show evidence of strong phylogenetic effects and stasis. In this contribution, we show how phylogenetic comparative methods can be used to test hypotheses that may help resolve this paradox. As a test case, we studied the interplay between adaptation and phylogenetic inertia on the thermobiology of 32 species of Liolaemus (Squamata: Liolaemidae), a genus of South American lizards living under diverse climatic conditions. Despite a strong phylogenetic effect in the preferred (selected) body temperature, we found clear evidence that this variable is adapted to local temperature and climate. After controlling for adaptation to the thermal environment, little influence of phylogeny was left. This indicates that the phylogenetic effect was not caused by a lag or slowness in adaptation but primarily by the distribution of the thermal environments on the phylogeny. This can be due to thermal niche tracking. In contrast, we found little or no evidence for adaptation to the thermal environment in either cooling or heating rates, critical thermal minimum, or body size.

Abstract. A digraph is attached to any evolution algebra. This graph leads to some new purely algebraic results on this class of algebras and allows for some new natural proofs of known results. Nilpotency of an evolution algebra will be proved to be equivalent to the nonexistence of oriented cycles in the graph. Besides, the automorphism group of any evolution algebra E with E = E 2 will be shown to be always finite.

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Experimental tests were conducted with the lizard Liolaemus tenuis (Tropiduridae), to determine the potential sources of pheromones used in its chemical communication, centered in the phenomenon of self-recognition. During the postreproductive season, feces of both sexes and secretions of precloacal pores (present only in males) were tested. Stimuli were presented to lizards spread on rocks, and the number of tongue-flicks (TF) to the rocks was used as a bioassay to determine pheromone recognition. Feces contained pheromones involved in self-recognition, since lizards showed less TF confronted to rocks with suspensions of their own feces than with suspensions of feces of conspecifics or with water (control). In order to assess the chemical nature of self-recognition pheromones, feces were submitted to a sequential extraction with three solvents of increasing polarity, thereby obtaining three feces fractions. There were no differences in TF towards rocks with different fractions with own feces. Additionally, lizards showed similar TF to rocks with fractions of own and conspecific feces, suggesting that the separation procedure broke up a complex stimulus into parts that were not active individually as pheromones. Finally, males did not discriminate between precloacal secretions from themselves and from another male. It is possible that these secretions convey information relevant to or detectable by females only.

Species-specific recognition systems are fundamental to maintaining the cohesion of species, particularly when heterospecific matings are possible. Here, I examined whether species recognition may facilitate species isolation of Liolaemus lizards, for which up to seven closely related species with similar morphology and ecology may live in sympatry. I also tested whether coexistence with closely related species modulates species recognition. In three Liolaemus species that differ in their current need for species recognition, I investigated their abilities to discriminate chemical stimuli from conspecifics and closely related congeners. For two of these focal species, tests included sympatric and allopatric congeners. The third species, which lives without congeners, was only tested with an allopatric congener. All three species chemo-discriminated between conspecifics and congeners, responding more vigorously to scents produced by their own species. Thus, chemical stimuli may help to maintain reproductive isolation. The existence of species recognition in the allopatric species may be an ancestral trait or may have evolved as a side effect of a within-species recognition system.

The type and several invariant subspaces related to the upper annihilating series of finite-dimensional nilpotent evolution algebras are introduced. These invariants can be easily computed from any natural basis. Some families of nilpotent evolution algebras, defined in terms of a nondegenerate, symmetric, bilinear form and some commuting, symmetric, diagonalizable endomorphisms relative to the form, are explicitly constructed. Both the invariants and these families are used to review and complete the classification of nilpotent evolution algebras up to dimension five over algebraically closed fields.Spanish Ministerio de Economia y Competitividad Fondo Europeo de Desarrollo Regional (FEDER) MTM 2013-45588-C3-2-P Diputacion General de Aragon - Fondo Social Europeo (Grupo de Investigacion de Algebra) FONDECYT 112084