“Forms” of water mites (Acari: Hydrachnidia): intraspecific variation or valid species?

In many groups of organisms, especially in the older literature, it has been common practice to recognize sympatrically occurring phenotypic variants of a species as “forms”. However, what these forms really represent often remains unclear, especially in poorly studied groups. With new algorithms for DNA‐based species delimitation, the status of forms can be explicitly tested with molecular data. In this study, we test a number of what is now recognized as valid species of water mites (Hydrachnidia), but have in the past been treated as forms sympatrically occurring with their nominate species. We also test a form without prior taxonomical status, using DNA and morphometrics. The barcoding fragment of COI, nuclear 28S and quantitative analyses of morphological data were used to test whether these taxa merit species status, as suggested by several taxonomists. Our results confirm valid species. Genetic distances between the form and nominate species (Piona dispersa and Piona variabilis, COI 11%), as well as likelihood ratio tests under the general mixed‐Yule coalescent model, supported that these are separately evolving lineages as defined by the unified species concept. In addition, they can be diagnosed with morphological characters. The study also reveals that some taxa genetically represent more than one species. We propose that P. dispersa are recognized as valid taxa at the species level. Unionicola minor (which may consist of several species), Piona stjordalensis, P. imminuta s. lat., and P. rotundoides are confirmed as species using this model. The results also imply that future studies of other water mite species complexes are likely to reveal many more genetically and morphologically distinct species.     

Cryptic diversity in flathead fishes (Scorpaeniformes: Platycephalidae) across the Indo‐West Pacific uncovered by DNA barcoding

Identification of taxonomical units underpins most biological endeavours ranging from accurate biodiversity estimates to the effective management of sustainably harvested, protected or endangered species. Successful species identification is now frequently based on a combination of approaches including morphometrics and DNA markers. Sequencing of the mitochondrial COI gene is an established methodology with an international campaign directed at barcoding all fishes. We employed COI sequencing alongside traditional taxonomic identification methods and uncovered instances of deep intraspecific genetic divergences among flathead species. Sixty‐five operational taxonomic units (OTUs) were observed across the Indo‐West Pacific from just 48 currently recognized species. The most comprehensively sampled taxon, Platycephalus indicus, exhibited the highest levels of genetic diversity with eight lineages separated by up to 16.37% genetic distance. Our results clearly indicate a thorough reappraisal of the current taxonomy of P. indicus (and its three junior synonyms) is warranted in conjunction with detailed taxonomic work on the other additional Platycephalidae OTUs detected by DNA barcoding.     

Genetic evidence for prevalence of alloparental care in a socially monogamous biparental cichlid fish,Perissodus microlepis,from Lake Tanganyika supports the “selfish shepherd effect” hypothesis

Alloparental care – care for unrelated young – is rare in animals, and its ecological or evolutionary advantages or, alternative maladaptive nature, remain unclear. We investigate alloparental care in the socially monogamous cichlid fish Perissodus microlepis from Lake Tanganyika that exhibits bi‐parental care. In a genetic parentage analysis, we discovered a surprisingly high percentage of alloparental care represented by brood mixing, extra‐pair paternity and extra‐pair maternity in all broods that we investigated. The percentage of nondescendant juveniles of other parents, i.e., brood mixing, ranged from 5% to 57% (mean = 28%). The distribution of genetic parentage also suggests that this socially monogamous species has, in fact, polygamous mating system. The prevalence of genetically mixed broods can be best explained by two, not mutually exclusive hypotheses on farming‐out and fostering behaviors. In the majority of broods, the sizes of the parents’ own (descendant) offspring were significantly larger than those of the adopted (nondescendant) juveniles, supporting the ‘selfish shepherd effect’ hypothesis, i.e., that foster parents preferentially accept unrelated “smaller or not larger” young since this would tend to lower the predation risks for their own larger offspring. There was also a tendency for larger parents particularly mothers, more so than smaller parents, to care predominantly for their own offspring. Larger parents might be better at defending against cuckoldry and having foreign young dumped into their broods through farming‐out behavior. This result might argue for maladaptive effects of allopatric care for the foster parents that only larger and possibly more experienced pairs can guard against. It needs to be determined why, apparently, the ability to recognize one's own young has not evolved in this species.     

One size fits all? Determinants of sperm transfer in a highly dimorphic orb‐web spider

The evolutionary significance of widespread hypo‐allometric scaling of genital traits in combination with rapid interspecific genital trait divergence has been of key interest to evolutionary biologists for many years and remains poorly understood. Here, we provide a detailed assessment of quantitative genital trait variation in males and females of the sexually highly dimorphic and cannibalistic orb‐weaving spider Argiope aurantia. We then test how this trait variation relates to sperm transfer success. In particular, we test specific predictions of the one‐size‐fits‐all and lock‐and‐key hypotheses for the evolution of genital characters. We use video‐taped staged matings in a controlled environment with subsequent morphological microdissections and sperm count analyses. We find little support for the prediction of the one‐size‐fits‐all hypothesis for the evolution of hypo‐allometric scaling of genital traits, namely that intermediate trait dimensions confer highest sperm transfer success. Likewise, our findings do not support the prediction of the lock‐and‐key hypothesis that a tight fit of male and female genital traits mediates highest sperm transfer success. We do, however, detect directional effects of a number of male and female genital characters on sperm transfer, suggesting that genital trait dimensions are commonly under selection in nature. Importantly, even though females are much larger than males, spermatheca size limits the number of sperm transferred, contradicting a previous hypothesis about the evolutionary consequences of genital size dimorphism in extremely size‐dimorphic taxa. We also find strong positive effects of male body size and copulation duration on the probability of sperm transfer and the number of sperm transferred, with implications for the evolution of extreme sexual size dimorphism and sexual cannibalism in orb weavers.     

Integrating life history traits into predictive phylogeography

Predictive phylogeography seeks to aggregate genetic, environmental and taxonomic data from multiple species in order to make predictions about unsampled taxa using machine‐learning techniques such as Random Forests. To date, organismal trait data have infrequently been incorporated into predictive frameworks due to difficulties inherent to the scoring of trait data across a taxonomically broad set of taxa. We refine predictive frameworks from two North American systems, the inland temperate rainforests of the Pacific Northwest and the Southwestern Arid Lands (SWAL), by incorporating a number of organismal trait variables. Our results indicate that incorporating life history traits as predictor variables improves the performance of the supervised machine‐learning approach to predictive phylogeography, especially for the SWAL system, in which predictions made from only taxonomic and climate variables meets only moderate success. In particular, traits related to reproduction (e.g., reproductive mode; clutch size) and trophic level appear to be particularly informative to the predictive framework. Predictive frameworks offer an important mechanism for integration of organismal trait, environmental data, and genetic data in phylogeographic studies.     

The species identity and biogeography of Blanus (Amphisbaenia: Blanidae) in Lebanon

The genus Blanus Wagler, 1830 represents limbless, burrowing reptiles of the family Blanidae with disjunct circum-Mediterranean distribution. The recently described species Blanus alexandri Sindaco, Kornilios, Sacchi & Lymberakis, 2014 is known from south-eastern Turkey with a presumed occurrence in the Levant and Iraq. We provide here records from Lebanon and confirm the affiliation of Lebanese populations to this species by mitochondrial and nuclear DNA. Blanus alexandri comprises at least seven deeply evolved phylogenetic clades with up to 11% of uncorrected p-distances in their mitochondrial DNA. This suggests a probably older than the Miocene origin of some of these clades. Populations from Lebanon form a different clade with a genetic diversity that is close to populations from southern Turkey.     

Sexual selection and its evolutionary consequences in female animals

For sexual selection to act on a given sex, there must exist variation in the reproductive success of that sex as a result of differential access to mates or fertilisations. The mechanisms and consequences of sexual selection acting on male animals are well documented, but research on sexual selection acting on females has only recently received attention. Controversy still exists over whether sexual selection acts on females in the traditional sense, and over whether to modify the existing definition of sexual selection (to include resource competition) or to invoke alternative mechanisms (usually social selection) to explain selection acting on females in connection with reproduction. However, substantial evidence exists of females bearing characters or exhibiting behaviours that result in differential reproductive success that are analogous to those attributed to sexual selection in males. Here we summarise the literature and provide substantial evidence of female intrasexual competition for access to mates, female intersexual signalling to potential mates, and postcopulatory mechanisms such as competition between eggs for access to sperm and cryptic male allocation. Our review makes clear that sexual selection acts on females and males in similar ways but sometimes to differing extents: the ceiling for the elaboration of costly traits may be lower in females than in males. We predict that current and future research on female sexual selection will provide increasing support for the parsimony and utility of the existing definition of sexual selection.     

Integrative taxonomy recognized a new cryptic species within Stipa grandis from Loess Plateau of China

Stipa shanxiensis, a cryptic species within Stipa grandis that originated from central and western China, is described based on morphological, genomic, and ecological data from field and common garden experiments. Stipa shanxiensis morphologically resembles S. grandis, although phylogenetically it is closely related to the less morphologically similar Stipa baicalensis and Stipa krylovii. Of the eight significant morphological differences between S. shanxiensis and S. grandis, the two, cauline ligules longer than 2 cm with a filiform apex, and hairs shorter than 0.2 mm on the adaxial surface of the cauline uppermost leaves can be used to distinguish the species. Results from a common garden experiment verified that the two diagnostic characteristics were relatively stable and less morphologically plastic in response to environmental variation. Furthermore, a significant ecological divergence was found between S. shanxiensis and S. grandis, such that the former preferred warmer and more humid climates, and their predicted distribution was generally separated. Taken together, our results highlight that the integrative taxonomic approach was valuable for recognizing a new cryptic species in Stipa. In particular, we find that common garden experiments involving the effects of growth stage and characteristic position helped to morphologically diagnose cryptic species. These findings may also facilitate our understandings of ecological adaption and phenotypic plasticity in response to environmental change.     

False promises: females spurn cheating males in a field cricket

Females commonly prefer to mate with males that provide greater material benefits, which they often select using correlated male signals. When females select higher-benefit males based on correlated signals, however, males can potentially deceive females by producing exaggerated signals of benefit quality. The handicap mechanism can prevent lower-quality males from producing exaggerated signals, but cannot prevent cheating by higher-quality males that choose to withhold the benefit, and this poses a major problem for the evolution of female choice based on direct benefits. In a field cricket, Gryllus lineaticeps, females receive seminal fluid products from males with preferred songs that increase their fecundity and lifespan. We tested the hypothesis that female behaviour penalizes males that provide lower-quality benefits. When females were paired with males that varied in benefit quality but had experimentally imposed average songs, they were less likely to re-mate with males that provided lower-quality benefits in the initial mating. This type of conditional female re-mating may be a widespread mechanism that penalizes males that cheat on direct benefits.