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Biol 321 > topic 5 > Flashcards

topic 5 Flashcards

1
Q

what is biogeography central to

A

evolutionary theory

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2
Q

what is biogeography? what does it explain?

A

• Study of geographic distributions of organisms over space and time
• Related to geology, paleontology, phylogenetics, ecology
• Study of what organism live where on earth and why
• Attempts to explain why species and higher taxa
are distributed as they are, and why the diversity
and taxonomic composition of the biota vary from
one region to another

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3
Q

what questions are posed by biogeographers?

A

• Why is a species or higher taxonomic group confined to its present range?
• What enables a species to live where it does, and what prevents it from colonizing other areas?
• How do different kinds of organisms replace each other as you go up a mountain or move from a rocky shore to a sandy beach nearby?
• What are a species’ closest relatives and where can they be found?
• Where did its ancestors live?
• How have historical events - such as, plate tectonics, Pleistocene
glaciation, and recent climate change - shape a species’ distribution?
Why are some groups of closely related species confined to the same
region while others are found on opposite sides of the world?
+ Why there are more species in the tropics than at temperate or arctic
regions?

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4
Q

define historical geography

A

Study of historical changes in geographic distribution of

organisms, including those that affect their present distribution

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5
Q

define ecological biogeography - why study it?

A

Current factors that affect present distributions
Studies the factors that define spatial distribution of species in
present time
Environmental factors such as, temperature, humidity, salinity act
as key elements in ecological biogeography
Global warming may lead to range expansions, dispersal events,
and new invasions
Study done by Alberta Biodiversity Monitoring Institute
4.6 - 15.2% decline in all six herds Of caribou With ranges in the Oil-
sands region of Alberta from 1993-2012

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6
Q

define endemic and dispersal

A

• Endemic
○ Restricted to a specific region or locality
• Dispersal
Extension of geographic range of a species

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7
Q

define vicariance. major disgareements?

A

Separation Of a continuously distributed ancestral species into
separate populations due to geographic or ecological barrier
•:• Major disagreement over
- Areas of endemism & centresof origin
Also 0’,’er importance of dispersal & vicariance events

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8
Q

describe dispersal biogeography

A

• Movement, active or passive, of individuals
to areas new to the existing population
• Distribution largely due to dispersal
Centre of origin
• Recently evolved & competitively superior
species arise in the centre of origin while
primitive species occur in the periphery
Barriers may be involved as well

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9
Q

describe Vicariance biogeography

A 
• Fragmentation of a former continuous 
	distribution of ancestral group into 
	geographically separated units through 
	appearance of a barrier, such as a result of 
	plate tectonics 
	• Dispersal has a secondary role 
•Cosmopolitan distribution - barrier - 
disjunct distribution 
•Primitive species in centre of origin; more 
derived forms in the periphery
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10
Q

Patterns of distribution of species across the globe

A

Geographic regions have characteristic biotas
Similar/closely related taxa tend to be closer
together than more distantly related groups
Similar environments are found in different areas
BUT the same species may not be found in all
places where they could be!

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11
Q

Major patterns of distribution - biogeographic regions- questions

A 
\+ Why is it that major taxa are 
confined to distinct regions? 
\+ Such phenomena influenced Darwin 
and Wallace greatly 
\+ Could such examples Of endemism 
(z restricted) have an evolutionary 
and historical explanation? 
\+ e.g., the catarrhine (old world) 
monkeys of Africa (below right) and 
the platyrrhine (new world) 
monkeys of South and Central 
America (upper left)
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12
Q

Wallace proposal - realms

A

Biogeographic realms: all except the Antarctic were proposed by A. R. Wallace
Large spatial regions
— Based on similarity in distribution & uniformity of biota-composition within
rezions than between them
share a broad similar evolutionary history

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13
Q

biogeographical relams for each continent?

what is wallaces line

A

Wllace’s Line is a boundary line drawn that separates the biogeographical realms of Asia and Wallacea, a transitional zone between Asia and Australia.
still recognized regions today

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14
Q

convergence ex.

A

— convergence: often seen in distantly related groups isolated on different
continents
— below: three distantly related families of plants (leafless succulents) with
ntations to drv environments
1. NA cactus 2. carrion flower africa and asia 3 euphorb africa

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15
Q

ex of convergence in animals - marsupials

A

marsupials of aus and SA vs placental mammals of NA, EUR, ASA, AFR
can fit into categories like cat, ant eater, mouse, wolf, etc but are from very different contients
There is a species of marsupials that can show any of these characterstic similarities - convergence not relation

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16
Q

study geological time scale again

A

ok

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17
Q

when was ice age? where did it impact

A

ce age: pleistocene epoch

• Impact in europe, north america, australia

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18
Q

when was plestocene? what happened during this epoch?

A

+ The first epoch in Quaternary period
during Cenozoic Era
2,588,000- 11,000 years ago
cooling began near end of pliocene (3mya) - reached a peak at 100,000 mya - wisconsin glaciation in NA; Wurm glaciation in europe

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19
Q

what happened at peak of ice age? what are we seeing now?

A 
sea levels dropped as much as 100 m
below current level -> Bering Land 
Bridge between Asia & North America 
-existed Off and on for almost 60 
million years 
-was a tundra-covered plain during the 
Pleistocene ice age 
opposite event now
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20
Q

what did bering land bridge connect? what did it do for animals?

A

siberia and alaska
• Dispersal and eventual extinction
Mammoth, giant ground sloth, saber-toothed tiger

21
Q

when was the late pleistocene extinction? what notable animals?

A

-11 ,OOO years ago
• Mostly mammalian species larger than -45 kg
Saber-toothed cats, mammoths, mastodons, giant
beaver

22
Q

three possible mechanisms of pleistocene extinction

A

anthropogenic, environmental changes, hyper disease

23
Q

describe anthropogenic theory

A

First human settlement in N Am -14,000 years ago
set the timing years , 2017:
Large species hunted down directly, or over-hunting eliminated
“keystone species”
Criticism: Were early human hunters sufficiently numerous &
technologically advanced?

24
Q

describe environmetal changes theory

A

Environmental changes
Rapid change of climate between 18,000 & 11 ,500 years ago
through rapid warming causing fundamental changes in the
ecosystems of N Am leading to extinction of larger species

25
Q

describe hyper disease theory

A

Hyper-disease
New human migrants brought in many disease-causing agents with
them and with their pets (mainly dogs)
dogs domesticated around this time

26
Q

how did the pleistocene extinctions affect each continent

A 
Mammalian megafauna affected: 
Africa: 5 species (18%) 
Australia: 14 species (88%) 
Eurasia: 5 species (36%) 
North America: 28 spp. (72%) 
South America: 49 (83%) 
Northern Hemisphere: Human 
impact with pronounced climate 
change. 
Southern Hemisphere: Humans 
helped to cause extinction but 
evidence of correlation with climate 
is weak.
27
Q

describe what wallaces line is

A 
Sea level lowering allowed 
spread of species across 
Southeast Asia 
Malay Archipelago was 
an extension of SE Asia 
New Guinea was 
connected to Australia 
Wallace's Line 
Organisms related to 
Asiatic species: west 
of the line 
Mixture of species of 
Asian & Australian 
origin: east of the 
line 
occurred from bali to lombok 
	• In land connection between the land - even shown today by bird species that observe that line - do not find the same species in bali and lombok
28
Q

what does dispersal do? darwin ex

A 
• Extension of a taxons geographic range to an area not previously occupied 
	• House sparrows, 
	lamprey, Darwin's 
	finches in the Galapagos 
	• Great American Biotic 
	Interchange between 
	North & South America 
	for terrestrial mammals 
via Isthmus of Panama
29
Q

dispersal rate in pleistocene?

A 
• Spread of species into glaciated areas 
	• Last 10,000 - 12,000 yrs 
	• Rate of dispersal varies 
	• Given enough time, even 
	slow-moving trees reach 
	their preferred habitat - but 
some haven't made it yet.
Alberta is a good example of 
this, since nearly all the 
present fauna and flora 
migrated here following the 
retreat of the glaciers 
-10,000 years ago 
chest nut ex
30
Q

dispersal ex starlings

A

• Expansion of the range of starlings - released in central park NY (they are from EU)
By 1970 they covered almost all of NA

31
Q

dispersal recent example cattle

A

• Cattle egret with water
buffalo
○ Feeding on insects stirred by grazing ungulates
○ Originally in tropical and subtropical parts of Old
World (Europe & Asia) until 80 years ago
○ Now also in warmer parts of
New World (South & North
America) to follow grazing
ungulates

32
Q

how did crickets in hawaii disperse

A 
•:• Island age matches the sequence 
of lineage splits 
•:• Dispersal to new islands caused 
isolation, leading to speciation 
\+ Successively younger groups 
found on younger islands 
\+ Empty ecological niches lead to 
adaptive radiation
33
Q

what is phylogeny biogeography? rules?

A

• Brand of historical biogeography
○ Proposed by L Z Brundin in a series of articles
Rests on hennig’s deviation and progress rules
Deviation rule: One species is always more apomorphic
in a pair of sister species
Progression rule: Apomorphic species more
peripherally distributed than the plesiomorphic sister
species

34
Q

vicariance and distribution?

A

• Division of a formerly continuous range by
geographic barriers and/or extinction in
intervening areas; disjunct distribution of
saxifrage.
• Distributions of monophyletic groups over areas
are explained by the reconstruction of area
cladograms
• Congruence (= agreement) of area cladograms of
different taxa strengthens argument
• Lack of congruence suggests that dispersal &
local extinctions important
• Group analysis to draw a cladogram - area cladogram

35
Q

look at dispersal vs vicariance diagram

A

ok

36
Q

what are relic populations?

A
  • Historical factors affecting geographic distributions
    • Relict populations: Remnants of, at one time, a much more diverse taxon.
    • Example: Saxifrage (Saxifraga cernua) - Holarctic with relict pops. In mountainous areas of the Alps, Norway, Iceland, Siberia, & Alaska.
37
Q

how can we explain relics?

A

Relics Can be explained by vicariance - now separated into patches of populations

38
Q

what is disjunct? ex?

A

• Ex 2 pygmy white fish
• Disjunct distribution: Two or more related taxa or
populations occurring in geographically separated areas
glacial melt in winage lakw ontario and lake superior
central distribution from isolation, genetic divergence, and selective dispersal from several pleistocene refugia including missisppi missour

39
Q

is glacial distribution vicariance

A
  • Found that current distribution is resulted by above thru genetic analysis
    • Not true vicariance event - post glacial dispersal
    • Similar story w deepwater sculpin - as ice retreated, it pushed relic pops at the two ends
40
Q

look at land mass distribution. timeline?

A
  1. permian 250 mya = pangea
  2. triassic 200 mya== laurasia and gondwanaland
    jurassic 145 mya = separate contients start to form, SA and africa close,
  3. cretaceous 65 mya = split of SA and Afr
    present day
41
Q

look at how gondwana broke up w madagascar

A

ok

42
Q

what explains gondwanan distributions

A 
• Vicariance - most plausible explanation 
Breakup of Gondwana isolated descendant 
groups of a common ancestor 
- Examples: Cichlid fishes, Lemurs of 
Madagascar, Cichlids

ex.cichlids phylogeny is congruent w vicariant separation of clades caused by split of gondwana

43
Q

what can lemurs show us about the land division

A

• Lemurs of madagascar
• Came from african and asian lineage
• But, diverged well after madagascar spearated from other gondwanan landmasses
• Sister groups- can show us they have african and asian origin
• Madagascar remained separate from other landmasses for at leasr 88 my
• World - wide forest fires at end of creatceous period - all of madagascar got wiped out 65 mya
• Oldest age of origin determined from multiple sources including DNA and fossil analyses
○ 62 mya, long after Madagascar separated from african contient and they were NOT there when separation happened
hence- came to madagascar by migration, not vicarience

44
Q

watch lemur video and know info presented about their origin in madagascar

A

ok

45
Q

Historical biogeographic analysis: Seychelles tiger chameleon describe

A

• Study in 2011 -
• Multilocal genetic study
• India, madagascar, seychelles were separated from africa over 100 mya
• Seychellean tiger chameleon - sister taxon to southern african clade
• Divergence dating and biogeographic analyses indicate origin by transoceanic dispersal from africa to seychelles in eocene-oligocene epoch - 35 mya
Explained by dispersal

46
Q

gondwana distribution of ratitue birds, why are they mostly southern?

A

• Mostly southern contient distribution
Study in 2021
dispersal or vicariance

47
Q

ratite birds - dispersal theory

A 
Ancestor originally 
distributed in one Of the 
areas - "centre of origin" 
Dispersed to other areas by 
crossing a barrier 
Barrier predates disjunction
48
Q

if vicariance ratite birds

A 
Ancestor distributed in a 
widespread area 
Area became fragmented by 
successive barriers 
This geographic distribution 
followed by allopatric 
speciation 
Appearance of barrier 
causes geographic division
49
Q

ratite birds - which theory is correct?

A

Both are equally likely - not mutually exclusive
ex. •:• Formation of Isthmus of Panama -3 mya
- Simultaneously a vicariant event for marine organisms
between Atlantic & Pacific oceans
& a dispersal event forming a new migration route
between North & South America for terrestrial
mammals
have to view it case by case to determine the mechanism

Biol 321 (22 decks)

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