Authors: Kurt Davis and Dustin J Marshall
Published in: Journal of Animal Ecology, volume 83, issue 2 (March 2014)
Offspring size is a trait of fundamental importance that affects the ecology and evolution of a range of organisms. Despite the pervasive impact of offspring size for those offspring, the influence of offspring size on other species in the broader community remains unexplored. Such community-wide effects of offspring size are likely, but they have not been anticipated by theory or explored empirically.
For a marine invertebrate community, we manipulated the size and density of offspring of a resident species (Watersipora subtorquata) in the field and examined subsequent community assembly around that resident species.
Communities that assembled around larger offspring were denser and less diverse than communities that assembled around smaller offspring. Differences in niche usage by colonies from smaller and larger offspring may be driving these community-level effects.
Our results suggest that offspring size is an important but unexplored source of ecological variation and that life-history theory must accommodate the effects of offspring size on com- munity assembly. Life-history theory often assumes that environmental variation drives intra- specific variation in offspring size, and our results show that the converse can also occur.
Davis K, Marshall DJ (2014) Offspring size in a resident species affects community assembly. Journal of Animal Ecology, 83, 322–331 PDF 274 KB doi:10.1111/1365-2656.12136
Authors: Philip L Munday, Rober R Warner, Keyne Munro, John M Pandolfi and Dustin J Marshall
Published in: Ecology Letters, volume 16, issue 12 (December 2013)
An increasing number of short-term experimental studies show significant effects of projected ocean warming and ocean acidification on the performance on marine organisms. Yet, it remains unclear if we can reliably predict the impact of climate change on marine populations and ecosystems, because we lack sufficient understanding of the capacity for marine organisms to adapt to rapid climate change.
In this review, we emphasise why an evolutionary perspective is crucial to understanding climate change impacts in the sea and examine the approaches that may be useful for addressing this challenge.
We first consider what the geological record and present-day analogues of future climate conditions can tell us about the potential for adaptation to climate change. We also examine evidence that phenotypic plasticity may assist marine species to persist in a rapidly changing climate. We then outline the various experimental approaches that can be used to estimate evolutionary potential, focusing on molecular tools, quantitative genetics, and experimental evolution, and we describe the benefits of combining different approaches to gain a deeper understanding of evolutionary potential.
Our goal is to provide a platform for future research addressing the evolutionary potential for marine organisms to cope with climate change.
Munday PL, Warner RR, Munro K, Pandolfi JM, Marshall DJ (2013) Predicting evolutionary responses to climate change in the sea. Ecology Letters, 16: 1488–1500 PDF 371 KB doi:10.1111/ele.12185
Authors: Hannah Ritchie and Dustin J Marshall
Published in: The Journal of Experimental Biology, volume 216 (August 2013)
For organisms with complex life histories, the direction and magnitude of phenotypic links among life-history stages can have important ecological and evolutionary effects.
While the phenotypic links between mothers and offspring, as well as between larvae and adults, are well recognised, the links between sperm phenotype and offspring phenotype have been less well explored.
Here, we used a split-clutch / split-ejaculate design to examine whether the environment that sperm experience affects the subsequent performance of larvae in the broadcast spawning marine invertebrate Galeolaria gemineoa. The environment that sperm experienced affected the developmental success of larvae sired by these sperm; larvae sired by sperm that experienced low salinities had poorer developmental success than larvae sired by sperm that experienced a normal salinity.
When we explored the interactive effects of the sperm environment and the larval environment with an orthogonal design, we found an interaction; when sperm and larvae experienced the same environment, performance was generally higher than when the sperm and larval environments differed. These effects could be due to selection on specific sperm phenotypes, phenotypic modification of the sperm or both.
Together, our results challenge the traditional notion that sperm are merely transporters of genetic material; instead, significant covariance between sperm and offspring phenotypes exists. Our study adds to a growing list that demonstrates that fertilisation does have a homogenising effect on the phenotype of the zygote, and that events before fertilisation during the gamete phase can carry through to affect performance in later life-history stages.
Ritchie H, Marshall DJ (2013) Fertilisation is not a new beginning: sperm environment affects offspring developmental success. The Journal of Experimental Biology, 216 (16), 3104–3109 PDF 254 KB doi:10.1242/jeb.087221