The brown anole dewlap revisited: do predation pressure, sexual selection, and species recognition shape among-population signal diversity?

Animal signalling structures are amongst the most variable characteristics, as they are subjected to a diversity of selection pressures. A well-known example of a diverse signalling system in the animal kingdom is the dewlap ofAnolislizards. Dewlap characteristics can vary remarkably among and within species, and also between sexes. Although a considerable amount of studies have attempted to disentangle the functional significance of the staggering dewlap diversity inAnolis, the underlying evolutionary processes remain elusive. In this study, we focus on the contribution of biotic selective pressures in shaping geographic variation in dewlap design (size, colour, and pattern) and dewlap display behaviour at the intraspecific level. Notably, we have tried to replicate and extend previously reported results hereof in both sexes of the brown anole lizard (Anolis sagrei). To do this, we assembled a dataset consisting of 17A. sagreiheterogeneous island populations from the Caribbean and specifically tested whether predation pressure, sexual selection, or species recognition could explain interpopulational variation in an array of dewlap characteristics. Our findings show that in neither males nor females estimates of predation pressure (island size, tail break frequency, model attack rate, presence of predatoryLeiocephaluslizards) or sexual selection (sexual size dimorphism) could explain variation in dewlap design. We did find thatA. sagreimales from larger islands showed higher dewlap display intensities than males from smaller islands, but the direct connection with predation pressure remains ambiguous and demands further investigation. Last, we could show indirect support for species recognition only in males, as they are more likely to have a ‘spotted’ dewlap pattern when co-occurring with a higher number of syntopicAnolisspecies. In conclusion, we found overall limited support for the idea that the extensive interpopulational variability in dewlap design and use inA. sagreiis mediated by variation in their biotic environment. We propose a variety of conceptual and methodological explanations for this unexpected finding.

Interpopulational and seasonal variation in the chemical signals of the lizardGallotia galloti

Communicative traits are strikingly diverse and may vary among populations of the same species. Within a population, these traits may also display seasonal variation. Chemical signals play a key role in the communication of many taxa. However, we still know far too little about chemical communication in some vertebrate groups. In lizards, only a few studies have examined interpopulational variation in the composition of chemical cues and signals and only one study has explored the seasonal effects. Here we sampled three subspecies of the Tenerife lizards (Gallotia galloti) and analyze the lipophilic fraction of their femoral gland secretions to characterize the potential interpopulational variation in the chemical signals. In addition, we assessed whether composition of these secretions differed between the reproductive and the non-reproductive season. We analyzed variations in both the overall chemical profile and the abundance of the two main compounds (cholesterol and vitamin E). Our results show interpopulational and seasonal differences inG. gallotiachemical profiles. These findings are in accordance with the high interpopulational variability of compounds observed in lizard chemical signals and show that their composition is not only shaped by selective factors linked to reproductive season.

Niphargus dancaui sp. nov. (Amphipoda, Niphargidae) – a new species thriving in sulfidic groundwaters in southeastern Romania

Niphargus dancaui sp. nov., previously referred to as Niphargus cf. stygius, was sampled from various groundwater sites in and near the town of Mangalia (SE Romania) and described with Movile Cave (a sulfidic, chemoautotrophically based ecosystem) as type locality. A short comparison with Niphargus stygius specimens from Slovenia was made, together with a morphological analysis of interpopulational variability. Males of N. dancaui sp. nov. were relatively large (17 mm), with long antennae, pereiopods and uropod III. Females were slightly smaller, with shorter antennae, pereiopods and uropod III. Interpopulational variability was noticed in the chaetotaxy of the telson lobes and uropod III. N. dancaui sp. nov. is morphologically very close to N. lessiniensis and N. tridentinus, two species present in northern Italy, but distinct genetically from them based on 28S rRNA sequences. Instead, the closest relative of N. dancaui sp. nov. sequenced so far for this marker is N. montanarius, which inhabits a sulfidic cave system in central Italy. The work presented here contributes to our knowledge of groundwater crustacean biodiversity in general and of the systematics of the genus Niphargus in particular.

Interpopulational variability of Pinus sylvestris L. in eight Polish localities expressed in morphological and anatomical traits of needles

Two-year old needles were collected from 272 standing trees of <i>Pinus sylvestris</i> L., representing 8 Polish populations. The needles were studied in respect to IS morphological and anatomical traits. The obtained data were subjected to multivariate statistical analysis in an attempt to delineate interpopulational variability. Multivariate analysis of variance with testing of statistical hypotheses and discriminant analysis were conducted. Mahalanobis distances were calculated between each of population in pairs and their significance was estimated using Hotelling T² statistics. On the basis of the shortest Mahalanobis distances a minimum spanning tree was constructed and on the basis of Euklidean distances hierarchy grouping was performed. A large majority of the populations was found to differ significantly from the remaining populations. The population from Bolewice proved to be most divergent. The principal variables which proved capable of discriminating between populations were found to include: needle length, the number of stomata on the flat side of the needle and the number of resin canals. Using Bryant's test, the studied populations were found to belong to two geographic groups: the North-Polish one or the South-Polish one.

Cytogenetical and morphological features reveal significant differences among Venezuelan and Brazilian samples of Mugil curema (Teleostei: Mugilidae)

Karyotype of M. curema from the Gulf of Mexico and Brazil have been reported as possessing chromosome complement with 2n=28 and FN=48, whereas specimens from Venezuela has been reported as possessing a diploid number 2n=24 and a conserved FN (48). Although at first sight this variation suggests the presence of a chromosomal intraspecific (interpopulational) variability, the possibility that we are dealing with two different species was examined. This work revisit the karyotypes of M. curema from Venezuela and Brazil, including new data on C-banding, and NOR localization, and compares morphologic characteristics of samples from both localities. Thus, besides diploid number, the constitutive heterochromatin distribution and NORs location, mark other differences between M. curema Cytotype 1 (2n=28; FN=48) and Cytotype 2 (2n=24; NF=48). Moreover, morphologic comparison revealed differences in the scale counts and pectoral fin rays: 35 scales in the middle body line and 15 pectoral fin rays in specimens possessing the karyotype 2n=28, compared with 37-39 scales in the middle body line and 17 pectoral fin rays in specimens with the karyotype 2n=24. These differences lead us to suggest that both cytotypes are not related merely to geographic polytipic variations but could correspond to different species.

Demography, genetic diversity, and population relationships among Argentinean Mapuche Indians

Fertility, mortality and migration data from four Mapuche Indian communities located along a 215-km NE-SW linear area in the Province of Río Negro, Argentina, were collated with genetic information furnished by nine blood group systems and by mtDNA haplogroups. The demographic and genetic data indicated a clear dichotomy, which split the four populations into two groups of two. Differing degrees of non-Indian exchanges was probably the main determining factor for this separation. Total genetic variability was very similar in all groups, and the interpopulational variability accounted for only 10% of the total variability. A low prevalence of the Diego(a) antigen among the Mapuche was confirmed. The fact that significant genetic heterogeneity and population clusters were found in such a small territorial region attests to the sensitivity of demographic and genetic approaches in unraveling human history.