Peter R. Teske

Bio: Peter R. Teske is an academic researcher from University of Johannesburg. The author has contributed to research in topics: Population & Biological dispersal. The author has an hindex of 28, co-authored 110 publications receiving 2408 citations. Previous affiliations of Peter R. Teske include Rhodes University & Flinders University.

A review of marine phylogeography in southern Africa

Abstract: The southern African marine realm is located at the transition zone between the Atlantic and Indo-Pacific biomes. Its biodiversity is particularly rich and comprises faunal and floral elements from the two major oceanic regions, as well as a large number of endemics. Within this realm, strikingly different biota occur in close geographic proximity to each other, and many of the species with distributions spanning two or more of the region’s marine biogeographic provinces are divided into evolutionary units that can often only be distinguished on the basis of genetic data. In this review, we describe the state of marine phylogeography in southern Africa, that is, the study of evolutionary relationships at the species level, or amongst closely related species, in relation to the region’s marine environment. We focus particularly on coastal phylogeography, where much progress has recently been made in identifying phylogeographic breaks and explaining how they originated and are maintained. We also highlight numerous shortcomings that should be addressed in the near future. These include: the limited data available for commercially important organisms, particularly offshore species; the paucity of oceanographic data for nearshore areas; a dearth of studies based on multilocus data; and the fact that studying the role of diversifying selection in speciation has been limited to physiological approaches to the exclusion of genetics. It is becoming apparent that the southern African marine realm is one of the world’s most interesting environments in which to study the evolutionary processes that shape not only regional, but also global patterns of marine biodiversity.

What limits the distribution of subtidal macrobenthos in permanently open and temporarily open/closed South African estuaries? Salinity vs. sediment particle size

Abstract: Thirteen estuaries in the Eastern Cape Province, South Africa, were assigned to one of four types of estuaries (river-dominated permanently open, marine-dominated permanently open, medium-sized temporarily open/closed and small temporarily open/closed), and macrobenthic zonation patterns were compared using multivariate statistics. Three major habitat zones were identified: two relating to substrate (a sand zone and a mud zone), and a third zone characterised by water of low salinity (≤2.2). These zones are inhabited by four major groups of macrobenthos. The distribution of two of these (estuarine endemic sand fauna and estuarine endemic mud fauna) is limited by the nature of the substratum, whereas the distribution of the other two (fauna originating from the marine habitat and oligohaline fauna) is limited by salinity. Estuarine endemics were present in all four types of estuaries. Marine fauna was numerically important only in permanently open systems, while oligohaline fauna was abundant only in the upper reaches of river dominated open systems. Medium-sized temporarily open/closed estuaries lacked both marine and oligohaline forms, but these were present to a limited extent in small temporarily open/closed estuaries. Hence, salinity is not the primary environmental variable determining zonation patterns in Eastern Cape estuaries, and particularly in temporarily open/closed estuaries, it is of minor importance.

Unexpected genetic structure of mussel populations in South Africa: indigenous Perna perna and invasive Mytilus galloprovincialis

Abstract: Genetic structure of sedentary marine organisms with planktonic larvae can be in- fluenced by oceanographic transport, larval behaviour and local selection. We analysed the pop- ulation genetic structure (based on mtDNA) of the invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna along the southern African coastline. Low genetic divergence of M. galloprovincialis confirms its recent arrival in South Africa. In contrast, the genetic structure of P. perna revealed strong divergence on the south-east coast, forming a western and an eastern lin- eage. The distribution of the 2 lineages is extraordinary. They overlap for ca. 200 km on the south- east coast, and the western lineage includes animals occurring on either side of a 1000 km break in distribution across the Benguela upwelling system. In cluster analyses, animals on the south coast grouped with others 1000s of km to the west, rather than with those only 200 km to the east. This genetic disjunction may be caused by the south-flowing Agulhas Current preventing larval dispersal, or by different selective forces acting on local populations. M. galloprovincialis spread eastward along the south coast for 15 yr, but its range extension has virtually ceased in the region of genetic disjunction in P. perna, again indicating an oceanographic barrier to larval dispersal or selection dri- ven by sharp gradients in environmental conditions. The results suggest that local selection can pro- duce genetic structure opposite to that predicted by oceanographic data and that determining the population structure of indigenous species with similar larval dispersal can help us understand domain expansion of invading species.

Implications of life history for genetic structure and migration rates of southern African coastal invertebrates: planktonic, abbreviated and direct development

Abstract: The amount of genetic structure in marine invertebrates is often thought to be negatively correlated with larval duration. However, larval retention may increase genetic structure in species with long-lived planktonic larvae, and rafting provides a means of dispersal for species that lack a larval dispersal phase. We compared genetic structure, demographic histories and levels of gene flow of regional lineages (in most cases defined by biogeographic region) of five southern African coastal invertebrates with three main types of larval development: (1) dispersal by long-lived planktonic larvae (mudprawn Upogebia africana and brown mussel Perna perna), (2) abbreviated larval development (crown crab Hymenosoma orbiculare) and (3) direct development (estuarine isopod Exosphaeroma hylecoetes and estuarine cumacean Iphinoe truncata). We hypothesized that H. orbiculare, having abbreviated larval development, would employ a strategy of larval retention, resulting in genetic structure comparable to that of the direct developers rather than the planktonic dispersers. However, regional population structure was significantly lower in all species with planktonic larvae, including H. orbiculare, than in the direct developers. Moreover, nested clade analysis identified demographic histories resulting from low levels of gene flow (isolation by distance and allopatric fragmentation) in the direct developers only, and migration rates were significantly higher in all three species having planktonic larvae than in the direct developers. We conclude that the amount of genetic structure within marine biogeographic regions strongly depends on the presence or absence of free-swimming larvae. Whether such larvae are primarily exported or retained, whether they have long or short larval duration, and whether or not they are capable of active dispersal seems to have little effect on connectivity among populations.

A comparison of the macrobenthic faunas of permanently open and temporarily open/closed South African estuaries

Abstract: Thirteen estuaries in the Eastern Cape Province, South Africa, were broadly categorised according to size and salinity distribution and were assigned to one of the following categories: permanently open estuaries having a strong salinity gradient between mouth and upper estuary, freshwater-deprived permanently open estuaries, medium-sized temporarily open/closed estuaries, and small, temporarily open/closed estuaries. The macrobenthos collected during surveys was then compared in terms of the following parameters: species composition, salinity, sediment mud content, density of macrobenthic animals, Hill's N0 (species richness), and Hill's N1 (diversity). Mud content was found to be the most important environmental variable responsible for biotic patterns found, and sites were consequently assigned to either a sand zone fauna, or a mud zone fauna. Both types of fauna are present in all estuaries sampled, with upper sites of river dominated estuaries having an additional oligohaline fauna, and freshwater-deprived estuaries providing habitat for many marine species. Small, temporarily open/closed estuaries have the highest macrobenthic density, whereas N0 and N1 are highest in freshwater-deprived permanently open systems. River-dominated permanently open estuaries tend to have lower macrobenthic densities, species richness, and diversities compared to estuaries in the other categories. No seasonal differences in these ecological indices were found within any of the estuarine categories.

The Ecology of Invasions by Animals and Plants

Abstract: Much as Rachel Carson's \"Silent Spring\" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic \"The Ecology of Invasions by Animals and Plants\" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. \"History has caught up with Charles Elton's foresight, and \"The Ecology of Invasions\" can now be seen as one of the central scientific books of our century.\"-David Quammen, from the Foreword to \"Killer Algae: The True Tale of a Biological Invasion\