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SPECIES INTERACTIONS EVOLUTIONARY ECOLOGY ECOLOGY OF DOMESTICATION Interspecific interactions Effect of species 2 on species 1 Effect of species 1 on species 2 + 0 - + Mutualism Commensalism Predation, etc. 0 Commensalism Neutralism Amensalism Amensalism Competition - Predation Parasitism Herbivory EXPLOITATION (one species derives a benefit at a cost to another) MUTUALISM (benefiting both species) COMPETITION (cost to both species) Many interactions involve COEVOLUTION Interspecific interactions Exploitative -- Predation Predation – morphological counterstrategies Predation – physiological counterstrategies Predation – behavioral counterstrategies Interspecific interactions -- Exploitative Mammal-plant interactions Herbivory – evolution of grazing Plant chemical defenses Mechanical defense of seeds Interspecific interactions -- Exploitative Mammal-plant interactions Forced dispersal Interspecific interactions -- Exploitative Parasitism & Disease -- host parasite coevolution Xenopsylla Yersinia Rattus Mephitis Lyssavirus Desmodus Ixodes Borrelia Peromyscus Odocoileus Parasite – host cospeciation Geomydoecus Geomys Interspecific interactions Mutualistic coevolution Ruminant endosymbionts Initially parasities Interspecific interactions Mutualism Mammal – plant mutualism pollination germination dispersal Often evolve from relationships that were initially exploitative Interspecific interactions Mammal-mammal mutualism Multi-species herds (ungulates) Mixed colonies (hyraxes) Shared roosts (fruit bats) Shared predator vigilance Badger – coyote hunting “partnerships” mutualism or exploitation? Interspecific interactions Domestication Food Transport Hunting & Guarding Disease control?? Fiber Family Canidae Dog – 15,000 ybp ASIA Canis “familiaris” Wild canids Canis aureus Asia, north Africa Canis latrans North America Canis lupus Northern Hemisphere Canis simensis Africa (Ethiopia) Canis rufus North America Family Canidae Wolf variability (Canis lupus) Mexican European British Columbian Tundra Iberian mt DNA Evidence of repeated backcrossing with wild wolves Indian Eastern Tibetan Family Canidae Dog breeds (relationships inferred from nuclear genes) Basal clade – Central Asia Northern Holarctic Africa Middle East Family Felidae Domestic cat – ca. 10,000 ybp North Africa, Middle East (probably multiple origins) Felis “catus” Felis sylvestris Family Equidae Domestic horse --- ca. 6,000 ypb ASIA Paleolithic horse Equus caballus przewalski Domestic ass ca. 6,000 ybp NORTH AFRICA Equus asinus Family Equidae Genetics 2N = 62 chromosomes 2N = 52 chromosomes 2N = 56 chromosomes 2N = 64 chromosomes Grevy’s zebra (Equus grevyi) 2N = 46 Mountain zebra (Equus zebra) 2N = 34 Plains zebra (Equus burchelli) 2N = 44 Family Equidae Hybridization Domestic horse/ass hybrids Mule (mare + male ass) Equus caballus X Equus asinus Hinny (stallion + female ass) “Zeedonk” E. asinus x E. burchelli “Zorse” E. caballus x E. burchelli All equid hybrids are sterile due to problems of chromosome pairing during meiosis Family Bovidae Domesticated cattle (Bos) -- 8000 – 9000 ybp Multiple origins (Asia, Europe, North Africa) Probable “hybrid” origin extinct Auroch (Bos primagenius) Wild cattle (Bos taurus) Gaur (Bos gaurus) Yak (Bos grunniens) Family Bovidae Domestic sheep 6000 ybp Middle East Mouflon (Ovis musimon) Domestic goat 10,000 ybp Middle East Bezoar (Capra aegagrus) Family Suidae Domestic pig 10,000 ybp Multiple sites (SE Asia, India, Europe, Middle East) Wild boar (Sus scrofa) Family Cervidae Reindeer 5000 ybp Northern Mongolia Caribou (Rangifer tarandus) Family Camelidae Bactrian Camel ca. 5000 ybp Iran Camelus bactrianus Dromedary ca. 5000 ybp Arabia Camelus dromedarius Family Camelidae Llama 6000 ybp South America Guanaco (Lama guanicoe) Alpaca 3000+ ybp South America Vicuña (Vicugna vicugna) The only large mammal domesticates from the Western Hemisphere Ecology of Domestication Types of domesticates Commensal (dog, cat) Not originally raised by humans but attracted to human modified habitats Captive (ungulates) Purposefully captured and raised by humans Six requirements for successful captive domestication (from: Jared Diamond 2002. Nature 418:700-707) 1) Generalist diet 2) Favorable life history (fecundity and growth rate) 3) Docile disposition 4) Captive breeding 5) Social grouping in herds 6) Low panic response Also – genetic “predisposition” for artificial selection (natural variability, hybridization) Geography of Domestication Predominance of Eurasia Why? Earliest agricultural economies Large selection of appropriate mammals
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