Susana A. M. Varela

Medicinal use of fauna by a traditional community in the Brazilian Amazonia

BackgroundZootherapy inventories are important as they contribute to the world documentation of the prevalence, importance and diversity of the medicinal use of animals in traditional human communities. The present study aims to contribute with a more valuable example of the zootherapy practices of a traditional community in the Brazilian Amazonia – the “Riozinho do Anfrísio” Extractive Reserve, in Northern Brazil.MethodsWe used the methods of participant observation and semi-structured interviews, applied to 25 informants. We employed the combined properties of two indices to measure the medicinal importance of each cited species to the studied community, as well as their versatility in the treatment of diseases: the well known Use Value (UV) and the Medicinal Applications Value (MAV) that we developed.ResultsWe recorded 31 species of medicinal animals from six taxonomic categories, seven of which are new to science. The species are used for the treatment of 28 diseases and one species is used as an amulet against snakebites. The five species with the highest UV indices are the most popular and valued by the studied community. Their contrasting MAV indices indicate that they have different therapeutic properties: specific (used for the treatment of few diseases; low versatility) and all-purpose (several diseases; high versatility). Similarly, the most cited diseases were also those that could be treated with a larger number of animal species. Ten species are listed in the CITES appendices and 21 are present in the IUCN Red List. The knowledge about the medicinal use of the local fauna is distributed evenly among the different age groups of the informants.ConclusionsThis study shows that the local fauna represents an important medicinal resource for the inhabitants of the protected area. The combined use of the UV and MAV indices allowed identifying the species with the highest therapeutic potential. This type of information about a species may be of interest to pharmacological research, and is crucial to its conservation, since it helps signaling the species that may undergo higher hunting pressures. Data on zootherapy can also be of interesting to ecologists by contributing to indicators of local biodiversity richness.

Incomplete species recognition entails few costs in spider mites, despite first-male precedence

The consequences of heterospecific matings may hinge on interspecies interactions, but also on characteristics of the intraspecies mating system, namely sperm precedence. Indeed, first-male precedence may entail costs of heterospecific matings that are usually overlooked in other systems, such as fertilization of oocytes that become unavailable to subsequent conspecific males or a decrease in female receptivity. Here, we used a system composed of two co-occurring haplodiploid spider-mite species with first-male precedence, Tetranychus urticae and Tetranychus evansi, to investigate (a) the potential costs of heterospecific matings and (b) whether mites avoid heterospecific mates. We found that heterospecific matings did not result in fertilized offspring (i.e. females). Moreover, fecundity (i.e. male offspring) of heterospecifically mated females did not differ from that of virgins, indicating that oocyte viability was not affected by heterospecific males. Furthermore, heterospecific matings did not trigger behavioural changes that typically derive from conspecific matings, namely reduced female receptivity for subsequent matings. In avoidance tests, we found that T. evansi females and T. urticae males mated as often with conspecifics as with heterospecifics, whereas T. evansi males and T. urticae females mated assortatively more often. Also, latency to copulation in virgin and mated females did not differ between conspecific and heterospecific matings, but matings between T. urticae individuals lasted longer than heterospecific matings. Therefore, heterospecific matings result in few costs despite first-male precedence and, concomitantly, species discrimination is low. Still, this study highlights the need to account for intraspecific mating systems in tests of the reproductive consequences of mating with heterospecifics.Significance statementIn species where the first male fertilizes all the offspring (first-male precedence), mating with individuals from other species often yields few benefits and entails potential costs in terms of future mating events. Yet, several species exhibit incomplete recognition of conspecifics. We here show that this is the case among two spider-mite species that co-occur under natural conditions. However, we also demonstrate that the cost of mating with the ‘wrong’ species is low, even though they exhibit first-male precedence.

Sex-biased dispersal, kin selection and the evolution of sexual conflict

There is growing interest in resolving the curious disconnect between the fields of kin selection and sexual selection. Rankins (2011, J. Evol. Biol. 24, 71–81) theoretical study of the impact of kin selection on the evolution of sexual conflict in viscous populations has been particularly valuable in stimulating empirical research in this area. An important goal of that study was to understand the impact of sex‐specific rates of dispersal upon the coevolution of male‐harm and female‐resistance behaviours. But the fitness functions derived in Rankins study do not flow from his models assumptions and, in particular, are not consistent with sex‐biased dispersal. Here, we develop new fitness functions that do logically flow from the models assumptions, to determine the impact of sex‐specific patterns of dispersal on the evolution of sexual conflict. Although Rankins study suggested that increasing male dispersal always promotes the evolution of male harm and that increasing female dispersal always inhibits the evolution of male harm, we find that the opposite can also be true, depending upon parameter values.

Negative Public Information in Mate Choice Copying Helps the Spread of a Novel Trait

Numerous field and laboratory experiments have shown that many species have the capacity for social learning, including mate choice decisions that can be influenced by witnessing the mating decisions of others. Here we develop a numerical model of mate choice copying that follows the population genetics tradition, consisting in tracking allele frequencies in a population over time under various scenarios. In contrast to previous evolutionary models, we consider both positive social information and negative social information because many mating systems are driven by males in pursuit of a mate and female refusal of copulation may provide negative social information. The inclusion of negative social information to mate choice copying helps the spread of a novel trait, even if female innate mate choice preference is biased toward the common male type. We argue that the presence or absence of copying might simply mirror the associated cost-benefit relationship of the mating system of a given species and suggest how to test this prediction.

Evolution of mating behavior between two populations adapting to common environmental conditions.

Populations from the same species may be differentiated across contrasting environments, potentially affecting reproductive isolation among them. When such populations meet in a novel common environment, this isolation may be modified by biotic or abiotic factors. Curiously, the latter have been overlooked. We filled this gap by performing experimental evolution of three replicates of two populations of Drosophila subobscura adapting to a common laboratorial environment, and simulated encounters at three time points during this process. Previous studies showed that these populations were highly differentiated for several life-history traits and chromosomal inversions. First, we show initial differentiation for some mating traits, such as assortative mating and male mating rate, but not others (e.g., female mating latency). Mating frequency increased during experimental evolution in both sets of populations. The assortative mating found in one population remained constant throughout the adaptation process, while disassortative mating of the other population diminished across generations. Additionally, differences in male mating rate were sustained across generations. This study shows that mating behavior evolves rapidly in response to adaptation to a common abiotic environment, although with a complex pattern that does not correspond to the quick convergence seen for life-history traits.

Sexual selection modulates genetic conflicts and patterns of genomic imprinting

Recent years have seen a surge of interest in linking the theories of kin selection and sexual selection. In particular, there is a growing appreciation that kin selection, arising through demographic factors such as sex‐biased dispersal, may modulate sexual conflicts, including in the context of male–female arms races characterized by coevolutionary cycles. However, evolutionary conflicts of interest need not only occur between individuals, but may also occur within individuals, and sex‐specific demography is known to foment such intragenomic conflict in relation to social behavior. Whether and how this logic holds in the context of sexual conflict—and, in particular, in relation to coevolutionary cycles—remains obscure. We develop a kin‐selection model to investigate the interests of different genes involved in sexual and intragenomic conflict, and we show that consideration of these conflicting interests yields novel predictions concerning parent‐of‐origin specific patterns of gene expression and the detrimental effects of different classes of mutation and epimutation at loci underpinning sexually selected phenotypes.

Despite reproductive interference, the net outcome of reproductive interactions among spider mite species is not necessarily costly

Some closely-related species have reproductive interactions between them. Here, we show that the outcome of such interactions is highly variable. We did crosses among 3 species of herbivorous spider mites that co-occur in the Mediterranean and found that, depending on the order and timings of matings, they could be negative, neutral or positive. Therefore, the study of such interactions needs to account for the details of mating events, as the devil may be in them!

How pre- and postcopulatory sexual selection influence male mating decisions in a promiscuous species

When females mate multiply, male reproductive success depends on both pre- and postcopulatory processes, including female choice and sperm competition. However, these processes can favour different mating tactics in males. Here we used the Trinidadian guppy, Poecilia reticulata, system to understand how this conflict is resolved. We asked whether knowledge of recent female mating history leads males to adjust their mating effort with respect to the time devoted to mating activity, and the frequency and the sequence of mating tactics employed. To do this we quantified male mating behaviour in three competitive scenarios: (1) Single, when a focal male arrives near a single female and remains alone with her; (2) First, when a focal male is joined by a rival male; and (3) Second, when a focal male arrives after a rival male. We hypothesized that males adjust their behaviour based on arrival order. If female sequential mate choice is the main process shaping male mating behaviours (favouring First males in guppies), males should avoid competition and invest most when Single. Alternatively, if last-male sperm precedence is the major driver of decision making, males should invest more in mating attempts in the Second scenario. Greatest investment when First implies an intermediate strategy. We found that order of arrival influenced mating decisions with most mating activity during the First rather than the Single and Second scenarios. This result suggests that both pre- and postcopulatory processes influence mating investment, and that individual males make contingent decisions to maximize both mating and fertilization success.

Mate-choice copying: A fitness-enhancing behavior that evolves by indirect selection: EVOLUTION OF FEMALE MATE-CHOICE COPYING

A spatially explicit, individual‐based simulation model is used to study the spread of an allele for mate‐choice copying (MCC) through horizontal cultural transmission when female innate preferences do or do not coevolve with a male viability‐increasing trait. Evolution of MCC is unlikely when innate female preferences coevolve with the trait, as copier females cannot express a higher preference than noncopier females for high‐fitness males. However, if a genetic polymorphism for innate preference persists in the population, MCC can evolve by indirect selection through hitchhiking: the copying allele hitchhikes on the male trait. MCC can be an adaptive behavior—that is, a behavior that increases a populations average fitness relative to populations without MCC—even though the copying allele itself may be neutral or mildly deleterious.

The relation between R. A. Fisher’s sexy-son hypothesis and W. D. Hamilton’s greenbeard effect

Recent years have seen a growing interest in the overlap between the theories of kin selection and sexual selection. One potential overlap is with regards to whether R. A. Fishers “sexy‐son” hypothesis, concerning the evolution of extravagant sexual ornamentation, may be framed in terms of W. D. Hamiltons greenbeard effect, concerning scenarios in which individuals carry an allele that allows them to recognize and behave differently toward other carriers of the same allele. Specifically, both scenarios involve individuals behaving differently toward social partners who exhibit a phenotypic marker, with linkage disequilibrium between marker and behavior loci ensuring genetic relatedness between actor and recipient at the behavior locus. However, the formal connections between the two theories remain unclear. Here, we develop these connections by: (1) asking what kind of greenbeard is involved in the sexy‐son hypothesis; (2) exploring the relationship between the problem of “falsebeards” and the “lek paradox”; (3) investigating whether these two problems may be resolved in analogous ways; and (4) determining whether population structure facilitates both of these evolutionary phenomena. By building this conceptual bridge, we are able to import results from the field of kin selection to sexual selection, and vice versa, yielding new insights into both topics.