PhD position open: the evolutionary ecology of sessile marine invertebrates

A PhD position is open to students interested in working on the evolutionary ecology of sessile marine invertebrates in Professor Dustin Marshall’s group.

The Marine Evolutionary Ecology Group’s research ranges from quantitative genetics to community ecology. Most projects are field-based with a heavy empirical component. The specifics of the project will be determined by joint collaboration between student and supervisor.

After an expression of interest, approved applicants would be required to apply for a scholarship and tuition waiver through Monash University by 15 April 2014.

The success of such applications is not assured and the application process is extremely competitive, students without at least one first-author publication in an international journal (in the topic of ecology or evolution) will not be considered.

The stipends include all course fees plus approximately $25,000 AUD per annum, tax-free (the equivalent of approximately $33,000 before tax) with no teaching requirements for 3.5 years (the length of a PhD in Australia).

Should the applicant be successful, the funding of project costs and research support including the costs of attending at least one conference per year will be provided by the research group.

Project start dates must be before 30 June 2014.

Interested applicants should send an expression of interest, their CVs, a brief statement of a potential research project and the contact details of two referees to dustin.marshall@monash.edu.

To be eligible, applicants must have completed at least one year of post-graduate research in ecology or evolution.

Preference will be given to those with strong quantitative skills and publications in international journals.

The maintenance of sperm variability: context-dependent selection on sperm morphology in a broadcast spawning invertebrate

Authors: Darren W Johnson, Keyne Monro, and Dustin J Marshall

Published in: Evolution, volume 67, issue 5 (May 2013)

Abstract

Why are sperm so variable despite having a singular, critical function and an intimate relationship with fitness?

A key to under-standing the evolution of sperm morphology is identifying which traits enable sperm to be successful fertilizers. Several sperm traits (e.g., tail length, overall size) are implicated in sperm performance, but the benefits of these traits are likely to be highly con- text dependent.

Here, we examined phenotypic selection on sperm morphology of a broadcast spawning tube worm (Galeolaria gemineoa). We conducted laboratory experiments to measure the relationship between average sperm morphology and relative fertilization success across a range of sperm environments that were designed to approximate the range of sperm concentrations and ages encountered by eggs in nature.

We found that the strength and form of multivariate selection varied substantially across our environmental gradients. Sperm with long tails and small heads were favored in high-concentration environments, whereas sperm with long heads were favored at low concentrations and old ages.

We suggest variation in the local fertilization environment and resulting differences in selection can preserve variability in sperm morphology both within and among males.

Full paper

Johnson D, Monro K, Marshall DJ (2013) The maintenance of sperm variability: context-dependent selection on sperm morphology in a broadcast spawning invertebrate. Evolution, 67-5: 1383–1395 PDF PDF 889 KB doi:10.1111/evo.12022

Revisiting the classic biogeographical patterns in marine invertebrate reproduction

After four years of data collection and over 4,000 papers, our paper revisiting the classic biogeographical patterns in marine invertebrate reproduction has been published here.

 Published paper: The biogeography of marine invertebrate life histories

Heat map of the distribution of studies used in the review to examine geographical variation in marine invertebrate life histories. The vast majority of the marine environment remains unstudied, and our view of marine life histories comes from only a small fraction of those studies that exist.