Heat stress mediates toxicity of rutile titanium dioxide nanoparticles on fertilisation capacity in the broadcast spawning mussel Mytilus galloprovincialis.

Titanium dioxide nanoparticle (nTiO) pollution of marine environments is rapidly increasing with potentially deleterious effects on wildlife. Yet, the impacts of nTiO on reproduction remain poorly understood. This is especially the case for broadcast spawners, who are likely to be more severely impacted by environmental disturbances because their gametes are directly exposed to the environment during fertilisation.

Resilience to periodic disturbances and the long-term genetic stability in Acropora coral.

Climate change is restructuring natural ecosystems. The direct impacts of these events on biodiversity and community structure are widely documented, but the impacts on the genetic variation of populations remains largely unknown. We monitored populations of Acropora coral on a remote coral reef system in northwest Australia for two decades and through multiple cycles of impact and recovery.

Divergence in the internal genital morphology of females and correlated divergence in male intromittent structures among populations of a millipede.

Our understanding of genital evolution comes largely from studies of male genitalia. Females have received far less attention because of the difficulties inherent in quantifying the shapes of their internal genital structures. Here we combine advances in micro-computed tomography with a new landmark free method of quantifying three-dimensional trait shape, to document patterns of divergence in female genital shape, and the correlated divergence of male genitalia among populations of the millipede Antichiropus variabilis.

The thermal environment of sperm affects offspring success: a test of the anticipatory paternal effects hypothesis in the blue mussel.

There has been an explosion of recent evidence that environments experienced by fathers or their ejaculates can influence offspring phenotypes (paternal effects). However, little is known about whether such effects are adaptive, which would have far-reaching implications for the many species facing rapidly changing environments. For example, some arguments suggest paternal effects might be a source of cross-generational plasticity, preparing offspring to face similar conditions to their father (anticipatory hypothesis).

Daily temperature cycles prolong lifespan and have sex-specific effects on peripheral clock gene expression in Drosophila melanogaster.

Circadian rhythms optimize health by coordinating the timing of physiological processes to match predictable daily environmental challenges. The circadian rhythm of body temperature is thought to be an important modulator of molecular clocks in peripheral tissues, but how daily temperature cycles affect physiological function is unclear. Here, we examined the effect of constant temperature (Tcon, 25°C) and cycling temperature (Tcyc, 28°C:22°C during light:dark) paradigms on lifespan of Drosophila melanogaster, and the expression of clock genes, heat shock protein 83 (Hsp83), Frost (Fst) and senescence marker protein-30 (smp-30).

Post-ejaculation thermal stress causes changes to the RNA profile of sperm in an external fertilizer.

Sperm cells experience considerable post-ejaculation environmental variation. However, little is known about whether this affects their molecular composition, probably owing to the assumption that sperm are transcriptionally quiescent. Nevertheless, recent evidence shows sperm have distinct RNA profiles that affect fertilization and embryo viability.

Genome-wide SNPs detect no evidence of genetic population structure for reef manta rays (Mobula alfredi) in southern Mozambique.

Little is known about the extent of genetic connectivity along continuous coastlines in manta rays, or whether site visitation is influenced by relatedness. Such information is pertinent to defining population boundaries and understanding localized dispersal patterns and behaviour. Here, we use 3057 genome-wide single-nucleotide polymorphisms (SNPs) to evaluate population genetic structure and assess the levels of relatedness at aggregation sites of reef manta rays (Mobula alfredi) in southern Mozambique (n = 114).

Experimental evidence for accelerated adaptation to desiccation through sexual selection on males.

The impact of sexual selection on the adaptive process remains unclear. On the one hand, sexual selection might hinder adaptation by favouring costly traits and preferences that reduce nonsexual fitness. On the other hand, condition dependence of success in sexual selection may accelerate adaptation.

Ocean acidification during prefertilization chemical communication affects sperm success.

Ocean acidification (OA) poses a major threat to marine organisms, particularly during reproduction when externally shed gametes are vulnerable to changes in seawater pH. Accordingly, several studies on OA have focused on how changes in seawater pH influence sperm behavior and/or rates of in vitro fertilization. By contrast, few studies have examined how pH influences prefertilization gamete interactions, which are crucial during natural spawning events in most externally fertilizing taxa.

Population Genomics of : Admixing Increases Genetic Diversity with no Evidence of Outbreeding Depression.

Small and isolated populations are subject to the loss of genetic variation as a consequence of inbreeding and genetic drift, which in turn, can affect the fitness and long-term viability of populations. Translocations can be used as an effective conservation tool to combat this loss of genetic diversity through establishing new populations of threatened species, and to increase total population size. Releasing animals from multiple genetically diverged sources is one method to optimize genetic diversity in translocated populations.

It's not all black and white: investigating colour polymorphism in manta rays across Indo-Pacific populations.

Intraspecific colour polymorphisms have been the focus of numerous studies, yet processes affecting melanism in the marine environment remain poorly understood. Arguably, the most prominent example of melanism in marine species occurs in manta rays ( and ). Here, we use long-term photo identification catalogues to document the frequency variation of melanism across Indo-Pacific manta ray populations and test for evidence of selection by predation acting on colour morph variants.

Mixing Genetically and Morphologically Distinct Populations in Translocations: Asymmetrical Introgression in A Newly Established Population of the Boodie ().

The use of multiple source populations provides a way to maximise genetic variation and reduce the impacts of inbreeding depression in newly established translocated populations. However, there is a risk that individuals from different source populations will not interbreed, leading to population structure and smaller effective population sizes than expected. Here, we investigate the genetic consequences of mixing two isolated, morphologically distinct island populations of boodies () in a translocation to mainland Australia over three generations.

A genome-wide search for local adaptation in a terrestrial-breeding frog reveals vulnerability to climate change.

Terrestrial-breeding amphibians are likely to be vulnerable to warming and drying climates, as their embryos require consistent moisture for successful development. Adaptation to environmental change will depend on sufficient genetic variation existing within or between connected populations. Here, we use Single Nucleotide Polymorphism (SNP) data to investigate genome-wide patterns in genetic diversity, gene flow and local adaptation in a terrestrial-breeding frog (Pseudophryne guentheri) subject to a rapidly drying climate and recent habitat fragmentation.

Evaluating the genetic architecture of quantitative traits via selection followed by inbreeding.

The deleterious mutation model proposes that quantitative trait variation should be dominated by rare, partially recessive, deleterious mutations. Following artificial selection on a focal trait, the ratio of the difference in inbreeding effects between control and selected populations (ΔB), to the difference in trait means caused by directional selection (ΔM), can inform the extent to which deleterious mutations cause quantitative trait variation. Here, we apply the ΔB/ΔM ratio test to two quantitative traits (male mating success and body size) in Drosophila melanogaster.

Molecular evidence supports a genic capture resolution of the lek paradox.

The genic capture hypothesis, where sexually selected traits capture genetic variation in condition and the condition reflects genome-wide mutation load, stands to explain the presence of abundant genetic variation underlying sexually selected traits. Here we test this hypothesis by applying bidirectional selection to male mating success for 14 generations in replicate populations of Drosophila melanogaster. We then resequenced the genomes of flies from each population.

Egg chemoattractants moderate intraspecific sperm competition.

Interactions among eggs and sperm are often assumed to generate intraspecific variation in reproductive fitness, but the specific gamete-level mechanisms underlying competitive fertilization success remain elusive in most species. Sperm chemotaxis-the attraction of sperm by egg-derived chemicals-is a ubiquitous form of gamete signaling, occurring throughout the animal and plant kingdoms. The chemical cues released by eggs are known to act at the interspecific level (e.

Multivariate Sexual Selection on Ejaculate Traits under Sperm Competition.

The widespread prevalence of sperm competition means that ejaculates face intense sexual selection. However, prior investigations of sexual selection on gametes have been hampered by two difficulties: (1) deriving estimates of relative fitness from sperm competition trials that are comparable across rival male and female genotypes and (2) obtaining measures of competitive fertilization success that are not confounded by postzygotic effects. Here, we exploit the experimental tractability of a broadcast spawning marine invertebrate to overcome these challenges and characterize multivariate sexual selection on sperm traits when multiple ejaculates compete.

Evolutionary divergence in competitive mating success through female mating bias for good genes.

Despite heritable variation for univariate sexually selected traits, recent analyses exploring multivariate traits find evidence consistent with the lek paradox in showing no genetic variation available to choosy females, and therefore no genetic benefits of choice. We used the preferences of females to exert bidirectional selection on competitive male mating success to test for the presence and nature of genetic variation underlying this multivariate trait. Male mating success diverged between selection regimens, and flies from success-selected lines had a smaller burden of deleterious, recessive mutations that affect egg-to-adult viability, were better sperm competitors (sperm offence), and did not demonstrate reduced desiccation resistance or components of female fitness (traits thought to trade off with attractiveness) relative to flies from failure-selected populations.

High levels of polyandry, but limited evidence for multiple paternity, in wild populations of the western rock lobster ().

Polyandry, where multiple mating by females results in the temporal and spatial overlap of ejaculates from two or more males, is taxonomically widespread and occurs in varying frequencies within and among species. In decapods (crabs, lobsters, crayfish, and prawns), rates of polyandry are likely to be variable, but the extent to which patterns of multiple paternity reflect multiple mating, and thus are shaped by postmating processes that bias fertilization toward one or a subset of mated males, is unclear. Here, we use microsatellite markers to examine the frequency of multiple mating (the presence of spermatophores from two or more males) and patterns of paternity in wild populations of western rock lobster ().

Genomic signatures of local adaptation reveal source-sink dynamics in a high gene flow fish species.

Understanding source-sink dynamics is important for conservation management, particularly when climatic events alter species' distributions. Following a 2011 'marine heatwave' in Western Australia, we observed high recruitment of the endemic fisheries target species Choerodon rubescens, towards the cooler (southern) end of its distribution. Here, we use a genome wide set of 14 559 single-nucleotide polymorphisms (SNPs) to identify the likely source population for this recruitment event.

Restricted gene flow and local adaptation highlight the vulnerability of high-latitude reefs to rapid environmental change.

Global climate change poses a serious threat to the future health of coral reef ecosystems. This calls for management strategies that are focused on maximizing the evolutionary potential of coral reefs. Fundamental to this is an accurate understanding of the spatial genetic structure in dominant reef-building coral species.

Phylogenomics provides new insight into evolutionary relationships and genealogical discordance in the reef-building coral genus Acropora.

Understanding the genetic basis of reproductive isolation is a long-standing goal of speciation research. In recently diverged populations, genealogical discordance may reveal genes and genomic regions that contribute to the speciation process. Previous work has shown that conspecific colonies of Acropora that spawn in different seasons (spring and autumn) are associated with highly diverged lineages of the phylogenetic marker PaxC Here, we used 10 034 single-nucleotide polymorphisms to generate a genome-wide phylogeny and compared it with gene genealogies from the PaxC intron and the mtDNA Control Region in 20 species of Acropora, including three species with spring- and autumn-spawning cohorts.

Plasticity of fertilization rates under varying temperature in the broadcast spawning mussel, .

Oceans are a huge sink for the increased heat associated with anthropogenic climate change, and it is vital to understand the heat tolerance of marine organisms at all life stages to accurately predict species' responses. In broadcast spawning marine invertebrates, reproduction is a vulnerable process in which sperm and eggs are released directly into the open water. Gametes are then exposed to fluctuating environmental conditions that may impact their fertilizing capacity.