1Ecological Convergence and its Effect on Ecological Convergence and its Effect on Fitness of Pelagic Fitness of Pelagic PlanktivoresPlanktivoresin African in African Great Lakes: Who Grows Better, Great Lakes: Who Grows Better, Cyprinids or ClupeidsCyprinids or Clupeids??African Rift LakesAfrican Rift Lakesz Ecological similarities in pelagic fauna in African Great Lakes2Ecological SimilaritiesEcological Similaritiesz Phylogeny = Common Evolutionary Historyz Parallelism and Convergence = Common Selective PressuresLake VictoriaLake Victoriaz Area = 68,635 km2 z Maximum Depth = 93 meters3Lakes Malawi and Tanganyika Lakes Malawi and Tanganyika z Lake Malawi– Area = 29,604 km2– Max Depth = 704 mz Lake Tanganyika– Area = 34,000 km2– Max Depth = 1470 mFauna Comparisons Fauna Comparisons z Clupeiformes = Most are open water, pelagic, schooling, 80% marine spp. 4 families, 83 genera, 363 speciesz Clupeidae– 66 genera, 222 species = herrings, shads, alewives, sprats, sardines, pilchards, menhadens, etc.4Comparisons Comparisons z Cypriniformes – 2660 speciesz Cyprinidae– 6 families, 284 genera, 2050 species; Almost all freshwater = minnows, shiners, carps, barbs, barbels, gudgeons, chubs, dace, squawfish, rudd, goldfish, koi, sharks, danios, etc. Phylogenetic ComparisonPhylogenetic ComparisonClupeocephala = Subdivision Clupeomorpha + Subdivision Euteleosteiz Clupeomorpha = Engraulidae + Clupeidae + Denticipitidae + Chirocentridaez Ostariophysi = Gonorhynchiformes + Cypriniformes + Characiformes + Siluriformes + Gymnotiformesz Cypriniformes = Cyprinidae + Gyrinochellidae + Catostomidae + Cobitidae + Balitoridae5Lake Tanganyika pelagic Lake Tanganyika pelagic fauna fauna z Clupeidaez Limnothrissa miodon (top)z Stolothrissa tanganicae(bottom)z Cyprinid – Chelaethiops(Engraulicypris) minutusLakes Victoria and Malawi Lakes Victoria and Malawi pelagic fauna pelagic fauna z Cyprinidaez Lake Victoria - Dagga– Rastrineobola argenteaz Lake Malawi - Usipa– Engraulicypris sardella6Changes in Lake Victoria Changes in Lake Victoria FaunaFaunaz Multi-species cichlid fisheryz Nile Perch dominated – three species – Lates niloticus– Oreochromis niloticus– RastrineobolaargenteaChanges in Lake Victoria Changes in Lake Victoria FaunaFaunaz Rastrineobolaargenteashows concurrent increase7RastrineobolaRastrineobolaargenteaargenteaz Zooplanktivorez 1.5 – 2 yr life span ??z 2ndmost important fisheryz Important resource for Nile perchz Little knownAge StudyAge Studyz Otolithsz Light and SEM countsz Individuals between 7.4 mm and 67.1 mm Standard lengthz 26 to 291 days old –They live less than one year8Model DescriptionsModel DescriptionsTable of Table of GompertzGompertzand von and von BertalanffyBertalanffyParametersParameters9GompertzGompertzModel Best FitModel Best FitGrowth PerformanceGrowth Performancez Φ = log k + 2 log L∝z Where k is Brody growth coefficient and L∝is von Bertalanffy asymptotic length z Attempt to measure the “growth performance” of a species by incorporating measures of maximum size and growth into one parameter10AllometricAllometricGraphs and Habitat Graphs and Habitat ShiftsShiftsAgeBody SizeRiverin ePelagicComparisons of Growth Comparisons of Growth PerformancePerformance11Species IntroductionsSpecies Introductionsz Pitcher et al. 1996 - lower Φ(earlier studies) suggest clupeid introduction into Lake Victoria z Φ’ calculated here for R. argentea is closer to other ecologically equivalent species. Introducing ecologically similar species to Lake Victoria to boost fishery production not supported.Productivity in Pelagic ZonesProductivity in Pelagic Zonesz Performance convergence of phylogenetic and ecologically diverse lineages z Incorporate growth rather than just per capita output into