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

skip

Two more types of selection

• Correlational – working on combinations of traits at once.

(body size)

(Wing length)

skip

• 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

Slow-loris

galago

• 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