Quantitative Ecology & Evolution

An ongoing collaboration among researchers from the University of Technology of Sydney, University of Sydney and the Macquarie University, in Sydney, the James Cook University and the Australian Institute of Marine Science in Townsville, and the Kochi University in Japan, resulted in a review paper published this week in the Journal Fish and Fisheries. The paper is a global review of tropical reef fish species occurring as vagrants in adjacent temperate zones, which shed light on the species-traits that predict species that may follow the pace of future climate changes and the ones that may be left behind and therefore more likely to become extinct. The paper shows that tropical vagrant species are more likely to originate from high-latitude populations, while at the demographic level, tropical fish species with large body size, high swimming ability, large size at settlement and pelagic spawning behaviour are more likely to show successful settlement into temperate habitats. [link]

New species evolve via two mechanisms, cladogenesis and anagenesis. Cladogenesis represents the subdivision of a species into two, reproductively isolated, independently evolving forms; whereas anagenesis represent within species evolution. In a study published in PNAS we identify the extent to which cladogenesis influences evolutionary dynamics. Using the fossil record of planktic Foraminifera, combined with modern molecular evidence, we find that cladogenesis is the predominant mechanism by which new species are established at macroevolutionary time scales (over millions of years). Our result has implications for understanding population genetics, community ecology and biodiversity. Our result also differs markedly from the conclusions of previous studies based solely of fossil data, and demonstrates the power of combining fossil data with genetic evidence.

In a study published in PLOS ONE, we explore two facets of climate change expected to detrimentally affect reef-building organisms by increasing their mortality rates and decreasing their calcification rates: increased tropical storm intensity and ocean acidification. We find that table coral populations are vulnerable to future collapse, placing in jeopardy many other reef organisms that are dependent upon them for shelter and food. Resistance to collapse is largely insensitive to predicted changes in storm intensity, but is highly dependent on the extent to which calcification influences both the mechanical properties of reef substrate and the colony-level trade-off between growth rate and skeletal strength.

The physical structure of coral reefs plays a critical role as a barrier to storm waves and tsunamis and as a habitat for living reef-building and reef-associated organisms. However, the mechanical properties of reef substrate (i.e. the non-living benthos) are largely unknown, despite the fact that substrate properties may ultimately determine where organisms can persist. In a study published in Coral Reefs, we used a geo-mechanical technique to measure substrate material density and strength over a reef hydrodynamic gradient. Contrary to expectation, we found a weak relationship between substrate strength and wave-induced water flow: flow rates decline sharply at the reef crest, whereas substrate properties are relatively constant over much of the reef before declining by almost an order of magnitude at the reef back. These gradients generate a novel hump-shaped pattern in resistance to mechanical disturbances for live corals, where colonies closer to the back reef are prone to dislodgement because of poorly cemented substrate. Our results help explain an intermediate zone of higher taxonomic and morphological diversity bounded by lower diversity exposed reef crest and unstable reef back zones

Our paper titled “Do Behavioral Foraging Responses of Prey to Predators Function Similarly in Restored and Pristine Foodwebs?” has been published in PLoS ONE. This study compares coral reefs with different histories of fishing pressure in the Line Islands in the central Pacific Ocean and the Great Barrier Reef in Australia. We show that prey behavioral responses to changes in the level of predation risk they face are bidirectional, and therefore that marine reserves designed to restore depleted predator populations may also have unexpected effects on prey behaviour.

Maina’s paper, “Modelling susceptibility of coral reefs to environmental stress using remote sensing data and GIS models” (2008, 212:180-199) has been listed as one of the most cited articles published in the journal Ecological Modelling since 2007. Congrats Maina!