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BLGY1124 > Bears > Flashcards

Bears Flashcards

1
Q

Obligate Carnivore

Definition

A

animals that depend soley on animal flesh for nutrient requirements

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2
Q

Facultative Carnivore

Definition

A

animal that depends on animal flesh for its nutrient requirements but also consumes non-animal food

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3
Q

Omnivore

Definition

A

animal that eats both animal and non-animal food

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4
Q

Apex Predator

Definition

A

at the top of the food chain

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5
Q

Homoplasy

Definition

A

a characteristic shared by a set of species that is not present in their common acestor

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6
Q

Extinct Bear Species

Arctotherium angustidens

A
  • largest bear ever found
  • south American
  • alive 2.5mya - 11kya
  • 3500Ibs / 250 stone
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7
Q

Extinct Bear Species

Ursus spelaeus

A
  • the cave bear
  • UK & Ireland
  • lived in caves only leaving to find food
  • especially limestone caves
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8
Q

Extinct Bear Species

Arctocus simus

A

-giant short faced bear

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9
Q

Extinct Bear Species

Ursus maritimus tyrannus

A
  • King Polar Bear
  • UK and Northern Europe
  • c. 130kya
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10
Q

Extinct Bear Species

Agriotherium africanum

A

-bear with the strongest bite

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11
Q

What has been the general trend in bear size over time?

A

they have become smaller

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12
Q

Modern European Carnivores

A
  • wolves
  • lynx
  • wolverine
  • eurasion brown bear
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13
Q

What is comparative genomics used to understand?

A
  • population movement
  • relationships between species (extant and extinct)
  • when a species diverged / emerged
  • what DNA changes or adaptations are unique to a species
  • what makes a species unique
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14
Q

Modern Bear Species

A 
Sun Bear
Panda
Sloth Bear
Spectacled Bear
Asiatic Black Bear
American Black Bear
Brown  / Grizzly Bear
Polar Bear
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15
Q

What are the closet non-bear relatives of extant bears?

A

racoon

lesser / red panda

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16
Q

Change in the Range of the Grizzly Bear Over Time

A

post-glacial - most of north America
historic - north and west America
modern - far north America, beginning to overlap with the range of the polar bear

17
Q

Polar Bear

A
  • diet is predominantly lipids and fats
  • tend to have twins or triplets as they release 2 eggs at a time
  • their milk is 27% fat
  • 50% body fat is healthy for an adult polar bear
  • diet is based on large quantities of seal fat
  • most carnivorous member of the bear family
  • they metabolise fat to get water so don’t need to drink
18
Q

Which bear is the closest relative of the polar bear?

A

the Grizzly bear

19
Q

Brown / Grizzly Bears

A
  • omnivores
  • long claws for digging
  • adapted to survive the changing seasons
  • have different diet in different seasons
  • may eat up to 40kg of food per day
  • can increase body weight by 1kg in a day
  • eat fruit, berries and nuts
20
Q

Tetrapod

Definition

A

has 4 limbs

21
Q

Homolog

Definition

A

a feature common to all descendants of a most recent common ancestor

22
Q

Homology

Definition

A

the existence of shared ancestry between a set/pair of structures/genes in different species e.g. fore limbs

23
Q

Alignment

Definition

A

positional homolog

24
Q

Mutation as a Molecular Clock

A
  • it is possible to count the number of mutations on a particular gene
  • in the alpha haemoglobin gene (NOT ALL GENES) the number of base substitutions is proportional to time as judged by the fossil record
25
Q

Genetic Diversity and Effective Population Size

A
  • genetic diversity is a function of effective population size
  • in a small population genetic diversity is relatively low
  • in a larger population genetic diversity is much greater
26
Q

Genetic Diversity

Brown Bears and Polar Bears

A

Polar Bears - 2.6 million unique mutations
Brown Bears - 7.7 million
Showing that polar bears have a much smaller effective population size than brown bears

27
Q

Reconstructing Ancestral Brow & Polar Bear Population Size

A 
900kya - 123k
big drop
500kya - 20k
TODAY
Polar - 68k
Brown - 463k
28
Q

When did Polar bears and Brown bears diverge?

A
  • molecular evidence - 470kya
  • fossil record - 479-343kya
  • mitochondrial DNA - 450kya
29
Q

Hybridisation - Polar and Brown Bears

A
  • at least 4 intragressive events
  • polar bears moved south and brown bears moved north
  • polar and brown bears interbred producing viable fertile offspring
  • these hybrid bears then interbred with both the polar bear and brown bear populations
  • then they separated north and south again
  • interbred separately for thousands of years
  • this means that the evolutionary history of brown bears and polar bears is interwoven and complex
30
Q

How did Polar bears adapt?

A
  • adipose tissue development
  • heart development
  • blood coagulation
  • homeostasis - regulation of body fluids
  • sarcomere organisation
  • white fur colouration
  • fatty acid metabolism
  • all adapted in a relatively short period of time
31
Q

Neutral Selection

Definition

A

non-advantageous, random genetic drift occurring

32
Q

Purifying Selection

Definition

A

pressure to retain the current genotype

33
Q

Positive Selection / Adaptive Evolution

A

pressure for change of the genotype to increase fitness

BLGY1124 (8 decks)

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