Frontiers of Biogeography

cover: Mouth of a Petromyzon marinus lamprey, taken at Aquarium Finisterrae (Coruña, Galicia, Spain). The original has been rotated. Picture by Drow male (http://commons.wikimedia.org/wiki/User:Drow_male), Creative Commons license.

Biogeography is a dynamic field that has transformed dramatically over the last few decades from being necessarily descriptive to become a rigorous science. Major recent areas of growth have included phylogenetics and phylogeography, microbial biogeography and metagenomics, and macroecology. However, the welcome recent deluge of massive amounts of data, in particular from genomics, museum specimens, and field observations, as well as environmental information, is posing a huge challenge to the field. The society has several key roles, not only to serve as a home for researchers in the field and enabling interaction among them, but also: (1) to provide a forum to facilitate awareness and use of rapidly developing tools and data; (2) to encourage a solid foundation in organismal research, with emphasis on field and museum based resources; (3) to promote global connections; and (4) to cultivate interdisciplinarity, such that the predictive capabilities of the field can be used to inform management and policy.

The Lusitania Province encompasses the warm temperate marine waters between the southern end of the English Channel, in the North, and Cape Juby or Cape Blanco, in the South, including the Mediterranean and the archipelagoes of the Azores, Madeira and the Canary Islands. Briggs and Bowen (2012) proposed that the warm temperate provinces, although retaining their provincial status, should be grouped with the adjacent tropical ones. Thus, they included the Lusitania Province in a warm eastern Atlantic region. We argue that the time elapsed since the Miocene was sufficient to allow the evolution of endemic species, genera and some higher rank taxa, a finding that emphasizes the convenience to avoid the integration of the province in this larger region. The tropicality index for the Lusitania Province is 1.82, indicating a prevalence of warm water over cold water fish. However, this value is strongly biased by the large differences between the Macaronesian archipelagos (4.08) and the mainland coasts of the Lusitania Province (0.66).

Numerous studies have demonstrated population genetic structuring in marine species, yet few have investigated the effect of vertical zonation on gene flow and population structure. Here we use three sympatric, closely related clinid species, Clinus cottoides, C. superciliosus and Muraenoclinus dorsalis, to test whether zonation on South African intertidal rocky shores affects phylogeographic patterns. We show that the high‐shore restricted species has reduced gene flow and considerably higher F_st values (F_st = 0.9) than the mid‐ and low‐shore species (F_st < 0.14). Additionally, we provide evidence for remarkably different demographic and evolutionary histories, ranging from extreme population bottlenecks to population persistence, which are probably linked to effective population size and habitat specialisation. This study further highlights the need for a multispecies approach to unravel the biological and evolutionary processes that drive extant population genetic patterns in marine species, as even closely related species with similar life histories show highly variable results.

The ways that organisms respond to climatic oscillations depend on a wide range of factors, including life-history, behaviour, thermal preferences and physiology, and ecology. To investigate these processes, we compared the phylogeographic patterns found in Lampetra fluviatilis and Petromyzon marinus in Europe. We reanalysed all molecular data available for the mitochondrial non-coding region subunit I for both species. For L. fluviatilis, we also analyzed new and existing data for ATPase subunits 6 and 8, which cover a wider geographic range. In L. fluviatilis, both gene diversity and nucleotide diversity are at least three times higher than in P. marinus in Europe. L. fluviatilis shows population differentiation in Europe and displays a deeper haplotype network, with no predominance of an ancestral haplotype, which contrasts with a star-like pattern for P. marinus. Bayesian skyline plots for the two species fit exponential models and, with estimates of the times to the most recent common ancestor in each species, indicate that P. marinus has much younger populations in Europe, supporting the hypothesis of its relatively recent migration from North America. The differences in phylogeographic structures of these two species are discussed considering the likely effects of differences in their thermal preferences, migration abilities, and times available for diversification.

Global climate change is correlated not only with variation in extinction rates, but also with speciation rates. However, few mechanisms have been proposed to explain how climate change may have driven the emergence of new evolutionary lineages that eventually became distinct species. Here, we discuss a model of range extension followed by divergence, in which the same climate oscillations that resulted in the extinction of coastal species across the Atlantic/Indian Ocean boundary in southwestern Africa also sowed the seeds of new biodiversity. We present evidence for range extensions and evolutionary divergence from both fossil and genetic data, but also point out the many challenges to the model that need to be addressed before its validity can be accepted.

It is now accepted that changes in the Earth’s climate are having a profound effect on the distributions of a wide variety of species. One aspect of these changes that has only recently received any attention, however, is their potential effect on levels of within-species genetic diversity. Theoretical, empirical and modelling studies suggest that the impact of trailing-edge population extirpation on range-wide intraspecific diversity will be most pronounced in species that harbour the majority of their genetic variation at low latitudes as a result of changes during the Quaternary glaciations. In the present review, I describe the historical factors that have determined current patterns of genetic variation across the ranges of Northern North Atlantic species, highlight the fact that the majority of these species do indeed harbour a disproportionate level of genetic diversity in rear-edge populations, and outline how combined species distribution modelling and genetic analyses can provide insights into the potential effects of climate change on their overall genetic diversity.

The advent of Sanger sequencing represented a scientific break-through that greatly advanced biogeographic studies. However, this technology has several limitations that have hampered more advanced studies in the field. The development of novel techniques which more fully exploit the potential of Massively Parallel Sequencing (MPS) to deliver sequence data at a fraction of the cost of Sanger sequencing promises to revolutionize biogeographic studies. Approaches like Restriction-site Associated DNA sequencing (RADseq) and UltraConserved Element (UCE) sequencing enable the collection of unprecedented amounts of data for multi-locus studies of population genetics and phylogenetics respectively, which in turn can be used for biogeographic analysis. Here we review those and other methods related to MPS, and provide examples of how they can be used in tropical Atlantic biogeography.