BIOL 1000 Lecture Notes - Lecture 17: Sciurus, The Parts Of Animals, Born Naked
2 Jul 2018
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7/2/18
BIOL 1000- EVOLUTION
14.1 SCIENTIFIC EVIDENCE TO SUPPORT EVOLUTION:
A. Fossil: series of fossils show transition of existing groups to new species.
B. Biogeography: geographical distribution of species.
C. Comparative Anatomy: comparison of body structures in different species; comparing de-
velopment in early stages of life which is comparative embryology.
D. Homology: similarity in characteristics that results from common ancestry; homologous
structures.
14.2 SPECIATION:
1. Speciation: the process by which one species splits into 2 or more species.
2. Biological species concept: a group of populations whose members have the potential to in-
terbreed in nature and produce fertile offspring.
3. Morphological species concept: classification based on distinguishing physical traits; can
be applied to fossils, asexually and sexually reproducing organisms; disadvantage because of
disagreement over distinguishing characteristics.
4. Ecological species concept: defines species in terms of ecological niches, focusing on adap-
tations for role in community.
5. Phylogenetic species concept: defines a species as the smallest group of individuals that
share a common ancestor and thus form one branch of the tree of life.
6. Hybrids: some species may interbreed which are resulting offsprings called hybrids; exam-
ple: Nanulak which is a hybrid if grizzly and polar bear; hybridization increasing because
climate change is eliminating reproductive barriers.
14.3 REPRODUCTIVE BARRIERS:
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7/2/18
I. PREZYGOTIC BARRIERS:
A. Habitat Isolation: species live in different habitats within the same areas and rarely meet; ex:
garter snakes.
B. Temporal Isolation: breeding occurs at different times of the day of different seasons;
ex:eastern and the western spots skunk breed in winters and summers respectively.
C. Behavioural Isolation: different courtship rituals or other behaviours prevent mate recogni-
tion between species; ex: blue footed booby performs an elaborate courtship dance and the
masked booby performs a different courtship ritual.
D. Mechanical Isolation: differences in physical structures prevent successful mating; ex: Heli-
conia pogonantha is pollinated by hummingbirds with long, curved bills and the Heliconia
latispatha is pollinated by hummingbirds with short, straight bills.
E. Gametic Isolation: male and female gametes of different species fail to unite; ex:purple sea
urchin and red sea urchin.
-(Fertilization occurs here)
II. POSTZYGOTIC BARRIERS:
A. Reduced Hybrid Viability: the development or survival of hybrids is impaired; ex:the hybrid
offspring of a horse and a donkey is a mule, which is robust and sterile.
F. Reduced Hybrid Fertility: hybrids fail to produce functional gametes.
G. Hybrid Breakdown: offspring of hybrids are feeble or infertile: ex: the rice hybrids (tall and
short).
-(visible, fertile offspring)
14.4 MECHANISMS OF SPECIATION:
1. Allotropic Speciation: the cause for most of diversity on Earth; populations sprayed by a
geographic barrier and geologic process can cause geographic barriers.
2. Sympatric Speciation: new species arises within the same geographic area as parent
species.
14.5 ADAPTIVE RADIATION EVIDENT ON ISLANDS:
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Document Summary
Nanulak ple: climate change is eliminating reproductive barriers. 14. 5 adaptive radiation evident on islands: islands: far enough apart to permit evolution in isolation but close enough to allow occa- sional gene flow. Example: galapagos archipelago born naked from underwater volcanoes, gradually colonized from other islands and south america. De partibus animalium: animal physiology and morphology. Species: sciurus vulgaris: phylogeny, binomial: genus name and species name of organism. Not as ambitious or misleading as common names. Always include the genus and the species name in that order. Capitalize the first letter of the genus only. Italicize binomial (or underline if handwritten): there are 150 different ways to classify 5 species and 13000000000000000000000 of differ- ent ways to organize 22 species. 7/2/18: phylogeny: the evolutionary history of species or group of species; fossil record chronicles evolutionary change and traces phylogeny of many groups; morphological similarities and molecular homologies determine phylogeny.
