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Flashcards in Evidence For Evolution Deck (38)
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1

The Fossil Record

• When fossils are arrayed in the order of their age, a progressive series of changes are seen
• Fossil records document the course of life through time

no outliers

2

evidence of evolution

o Evolutionary change in body size, crown height, molar base expansion, and toe reduction

as you get bigger, you get less toes ie. horses and their hooves

3

Transitional Fossils

from fishes --> land animals
Tiktaalik: intermediate between fish and land animals

4

Molecular Record

• The longer organisms have been separated according to the fossil record, the more differences are seen in the structure of their DNA

5

without errors

there would be no evolution
more mutations between species, the farther apart they in the fossil record

6

silent mutations in a protein

don't affect the amino acids and wont change the overall function of a protein

7

Nonsynonymous (missense) substitutions

do change the amino acid sequence and are likely to have an effect (often deleterious) on protein function; such substitutions are targets for natural selection.

8

cytochrome c

lack of variation across the sequences at positions 70-80 showing the similarity between organisms

suggests that this region is under strong stabilizing selection and that changing its amino acid sequence would impair the protein's function

9

Human Chromosome 2

great apes have 24 chromosomes

humans have 23 chromosomes

reasons we have 23 chromosomes is because great apes evolved and their two chromosomes became one chromosome aka Human chromosome 2

10

SRGAP2

Humans have four different versions of SRGAP2

primates have just one.

was duplicated in the human lineage about 3.4 mya, resulting in SRGAP2A and SRGAP2B

Further duplications of SRGAP2B gave rise to SRGAP2C about 2.4 mya and to SRGAP2D about 1 mya.

11

SRGAP2A

SRGAP2A, stimulates the maturation of dendritic spines

12

SRGAP2C

promotes an increased number of immature spines

might have played a major part in the emergence of the Homo lineage 2-3 mya

This development might have contributed to the evolution of human cognitive abilities.

13

SRGAP2 MUTATIONS

mutations of the gene in the brain's neocortex led to complex thought

14

Ostn genes

found in the muscles and bones of mammals

in humans its also found in neurons and provides clues to how humans evolved their cognitive abilities

15

opsin gene

tuned to a specific wavelength of light that helps us see different colors

Humans, apes and Old World primates have 3 separate opsin genes involved in color vision.

16

dichromat

see fewer than 20 color nuances

17

trichromat

See between 20 and 32 color nuances

18

tetrachromat

See between 32 and 39 colors nuances

19

short wavelength opsin gene

found on chromosome 7

all primates have it

20

medium and long opsin

found on the X chromosome
old world primates have medium and long=tetrochromatic

21

New world monkeys

mutations in genes that discontinued monkeys from having both medium and long wavelength

female new world monkeys have the potential to be trichromatic because since the medium and long wavelength is found on the X chromosome

male new world monkeys are only dichromatic because they only have one X chromosome meaning they can only be MW or LW

22

Homology vs Homoplasy

Homology is similarity due to common descent and homoplasy is similarity due to environment not common descent ie arctic: white fur

23

structural homology

inherited similar structures from a common ancestor

24

wings

between bats and birds
don't have common ancestor but due to their environment they have wings

25

convergent morphology

convergent evolution aka homoplasy

Similar anatomy evolved among lineages that independently adopted marine lifestyles

aka land animals became water animals and all developed fins

26

Developmental Homology

Developmental similarities reflect descent from a common ancestor

27

Genetic Toolkit

molecular factors that influence genes
DNA Replication, transcription, and translation

28

Hox genes

affect body position
can reorder the way organs are developed throughout the body

29

homeobox

All of the HOM and Hox genes share a 180-base-pair sequence

almost identical in insects and vertebrates

homology

30

hom and hox genes are similar

they specify the locations of cells in embryos.