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Acclimatization effects on final rectal temperature, heart rate, and sweat rate, for a group of men exposed daily to 2 hr of hard work in a hot environment. (after Leithead CS, Lind AR. Heat Stress and Heat Disorders. 1964. Philadelphia, Pa.: FA Davis Co, 304.
Fall 05 skip acclimitization
EMILI GARCÍA-BERTHOUOntogenetic Diet Shifts and Interrupted Piscivoryin Introduced Largemouth Bass (Micropterus salmoides)Internat. Rev. Hydrobiol. 87 2002 4 353–363
Fall 05 skip
acclimitization
Fall 05 skip acclimitization
Fall 05 skip acclimitization
Fall 05 skip acclimitization
Life Table
Fall 2005
Notes on Evolution,Natural Selection, and
Speciation
Fall 05 Start
One picture of evolutionWhat is going on before a split?How did the splits occur?What is speciation?
Types of evolution
• Macro• Micro
– Gene flow (E and I)• In isolated populations• Migrating indivs. start breeding• Immigrants can add new alleles• Not necessarily random
– Genetic Drift• Random mating in small populations• Causes relative success of only a fraction of individuals• Population bottlenecks (large population)• Founder effects (small population)
Mainland
migration
↑NA
↓NA
– Natural Selection• Differential contribution of offspring to next
generation by individuals in a population
• Not Random
Recall:Normal curve of phenotypic variationHeight of students in class
Another way to look at it…
• Directional Selection
Fitn
ess
Trait Trait
Positive Directional Selection Negative Directional Selection
Peppered Moth – Biston betularia
• Stabilizing selection
average trait value
Fitn
ess
Egg laying wasp that eventually kills the cactus
Malaria and Sickle Cell Anemia
SSA caused by mutation in the past…
• Disruptive Selection
average trait value
Fitn
ess
Black-bellied seed cracker (Pyrenestes ostrinus)
• Smith, T. B. 1990. Evolution. 44(4):832
• Black-bellied seed crackers (Pyrenestes) in Cameroon
Same birds different study
Open portion of bar – Number hatched
Black portion of bar – Number survived
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Two more types of selection
• Correlational – working on combinations of traits at once.
(body size)
(Wing length)
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• Frequency Dependent Selection – Level of selection dependent upon most common phenotype (at the time)
GenyochromisScale eater
Scalebiters – frequency dependent selection
Right “mouthedness” Left “mouthedness”
Time
Frequency of right “mouthedness”
Frequency of left “mouthedness”
• Selection can lead to speciation
• Speciation:– Splitting of one species into two or more species
(cladistic or punctuated).
– Transformation of one species into a new species over time (gradual or anagenic).
Anagenetic (gradual) versus Cladistic (punctuated) Speciation
A
AB
TIM
E
PHENOTYPICVARIATION
A
B
TIM
E
PHENOTYPICVARIATION
Species
• Many, many definitions
• Biological species definition: A group of actually or potentially breeding individuals which are reproductively isolated from all other groups.
• Doesn’t work in all situations– Fossils
– Asexual organisms
Isolating mechanisms
• Prezygotic –
• Postzygotic -
Prezygotic I.M.s
• Habitat isolation– Dendroica warblers in Eastern US
Modes of speciation• Allopatric – allo = different, patri = fatherland
• Sympatric – sym = together
• Has to do with location or habitat
Allopatric Speciation
Speciation occurs with reproductive isolation
Kaibab Squirrel
Abert’s Squirrel
Grand Canyon
Sympatric speciation
• Rare
• Polyploidy in plants
• Hybrids
Evolution &Speciation of Primates
including Homo
Divisions of Primates
• Prosimians (“before ape”)– Lemurs– Tarsiers– Lorises– Galagos
• Lemurssifaka
• Tarsier
• Lorises and Galagos
• New World Monkeys
• Old World Monkeys– Baboons– Macaques
Asian apes
• Gibbons
African Apes
• Chimps
• Gorillas
• Hominids
• etc…bonobo
Hominids
• Several genera
• Homo
4w human embryo
• Most Homonid adaptation related to bipedialism
• Sahelanthropus tchadensis– “Toumai child”– 6-7 MYA– Chad
• Ardepithecus ramidus– 5.8 – 4.4 MYA– Ethiopia
Australopithecines
• Genus Australopithecus
– Slender (“gracile”) forms• A. africanus, A. afarensis
– Robust forms• A. robustus, A. boisei, A. aethopicus
• A. africanus– South Africa– 3 – 2 mya– “slender” type
• A. afarensis– Slender form– “lucy”– East Africa– ~3mya
Dr. Corbin
• A. robustus– Robust form– Olduvai gorge– 1.8 mya
Genus Homo
• Homo habilis– 2.0 – 1.9 mya– Brain size 775 cc
• Speech centers
– Omnivore– Olduvai gorge
• H. habilis (cont.)
• H. erectus– Java– 1.9-0.3 mya– Brain 800-1000cc
• H. erectus (cont)
• Extensive tool use
• Fire
• Dispersed into Europe and Asia
• H. neanderthalensis– 200k bp– Neander valley– 1450 cc
• H. sapiens– Cromagnon man
• 100-150k bp
• ~1360 cc
• Culture
• Timeline of Homonid evolution
Thousands of years before present
Out-of-Africa Hypothesis
Note on human variability
• Ethnic - of or relating to large groups of people classed according to common racial, national, tribal, religious, linguistic, or cultural origin or background.
a b c d
Geneticvariation
Lewontin – 17 genes, 7 ethnic groups
Morphological differencesnot adaptive
…a b