Lecture 13 Zoogeography 1. Background 2. Continental drift and Glaciations 3. Zoogeographic areas 4. Methods / Tests
Lecture 13 Zoogeography Geographic distribution of animals past and present The challenge is to discern patterns among current distributions of taxa and how these patterns relate to their evolutionary history We will look at how and why different fishes got to where they are today
Zoogeography Alfred Russel Wallace (1823-1913) - father of biogeography 20 April 1854 (arrived in Singapore) - 1 April 1862 The Malay Archipelago
Wallace s line
Wallace s line Wallace was the first to realize that distribution of related species is fundamentally linked to geologic history of places the species inhabit
The Formation of Zoogeographic Regions Two main hypotheses: Dispersal Vicariance
DISPERSAL Island 1. Start with one continuous population. Then, a colonist floats to an island on a raft. Continent 2. Finish with two populations isolated from one another.
VICARIANCE River 1. Start with one continuous population. Then a chance event occurs that changes the landscape (river changes course). River changes course 2. Finish with two populations isolated from one another.
Continental Drift
Continental Drift Current arrangement of continents creates barriers among marine species Can separate populations of freshwater fishes
Continental Drift
Continental Drift
Glaciation
Glaciation Glaciations result in lower sea levels, which changes the dynamics of currents and ultimately gene flow Temperate fishes were massively displaced by glaciation retreating glaciers left behind postglacial lakes
Glaciation 120m below current sea level
Glaciation
Glaciation Esocidae (pikes and muskie)
Glaciation Parrotfishes (Scaridae) speciation events coincide with sea level lows
Marine Zoogeographic Regions Four major zones 1. Indo-West Pacific 2. Western Atlantic 3. Eastern Pacific 4. Eastern Atlantic
Marine Zoogeographic Regions Indo-West Pacific ~3000 spp. Contains coral triangle
Marine Zoogeographic Regions Indo-West Pacific coral triangle global maxima of marine biodiversity ~500 spp of reef building coral (10x the amount in the western Atlantic) number of taxa decrease as one proceeds eastward across Pacific plate
Marine Zoogeographic Regions Indo-West Pacific
Marine Zoogeographic Regions Western Atlantic ~1200 spp.
Marine Zoogeographic Regions Western Atlantic
Marine Zoogeographic Regions Western Atlantic Amazon river divides coral reef fish fauna into northern and southern parts by freshwater outflow Bottom trawls underneath the outflow reveal coral reef species assemblage but with sponges Genetic analyzes reveal there is some connectivity between the North and the South
Marine Zoogeographic Regions Western Atlantic
Marine Zoogeographic Regions Western Atlantic Three species of surgeonfishes in the genus Acanthurus were sampled throughout the Western Atlantic basin genetic connectivity was estimated The amazon outflow effected geneflow in each species uniquely strong barrier in A. bahianus A. bahianus A. coeruleus modest barrier A. coeruleus no effect in A. chiurgus A. chirurgus
Marine Zoogeographic Regions Eastern Pacific
Marine Zoogeographic Regions Eastern Pacific Related to and only recently separated from the western Atlantic around 3 mybp fewer spp of fishes and corals Geminate species The eastern Pacific barrier acts as a distance barrier limits 86% of reef species from central Pacific
Eastern Pacific Barrier
Holacanthus Distribution Alva-Campbell et al 2 Geminate Spp.?
geminate sister clades Holacanthus RADseq Phylogeny 1/100 HTR_CABR_020601 HTR_PAN_050704 H. tricolor 1/100 1/99 1/100 HBE_MKF_080701 HBE_MKF_110701 H. bermudensis TWA 1/100 HCI_CABR_020601 H. ciliaris HCI_MKF_080701 1/100 1/97 HCL_APA_050701 H. clarionensis 1/100 1/100 HLI_CLI_041001 HLI_CLI_041002 H. limbaughi TEP 1/98 HPA_MUE_061202 HPA_MUE_061201 H. passer 0.9 HAF_CVE_0999289 H. africanus 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Vicariance or dispersal? Mya Tariel, Longo, & Bernardi 2016
Marine Zoogeographic Regions Eastern Atlantic & Mediterranean
Marine Zoogeographic Regions Eastern Atlantic & Mediterranean Sparse coral cover in the tropical Gulf of Guinea Depauperate in spp (~ 600) After completion of Suez Canal, Lessepsian migrants have begun to invade the Mediterranean
After completion of Suez Canal, Lessepsian migrants have begun to invade the Mediterranean