topic 5

Question 1

what is biogeography central to

Answer 1

evolutionary theory

Question 2

what is biogeography? what does it explain?

Answer 2

• 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

Question 3

what questions are posed by biogeographers?

Answer 3

• 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?

Question 4

define historical geography

Answer 4

Study of historical changes in geographic distribution of

organisms, including those that affect their present distribution

Question 5

define ecological biogeography - why study it?

Answer 5

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

Question 6

define endemic and dispersal

Answer 6

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

Question 7

define vicariance. major disgareements?

Answer 7

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

Question 8

describe dispersal biogeography

Answer 8

• 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

Question 9

describe Vicariance biogeography

Answer 9

• 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

Question 10

Patterns of distribution of species across the globe

Answer 10

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!

Question 11

Major patterns of distribution - biogeographic regions- questions

Answer 11

\+ 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)

Question 12

Wallace proposal - realms

Answer 12

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

Question 13

biogeographical relams for each continent?

what is wallaces line

Answer 13

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

Question 14

convergence ex.

Answer 14

— 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

Question 15

ex of convergence in animals - marsupials

Answer 15

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

Question 16

study geological time scale again

Answer 16

ok

Question 17

when was ice age? where did it impact

Answer 17

ce age: pleistocene epoch

• Impact in europe, north america, australia

Question 18

when was plestocene? what happened during this epoch?

Answer 18

+ 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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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

Question 21

when was the late pleistocene extinction? what notable animals?

Answer 21

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

Question 22

three possible mechanisms of pleistocene extinction

Answer 22

anthropogenic, environmental changes, hyper disease

Question 23

describe anthropogenic theory

Answer 23

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?

Question 24

describe environmetal changes theory

Answer 24

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

Question 25

describe hyper disease theory

Answer 25

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

Question 26

how did the pleistocene extinctions affect each continent

Answer 26

``` 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. ```

Question 27

describe what wallaces line is

Answer 27

``` 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 ```

Question 28

what does dispersal do? darwin ex

Answer 28

``` • 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 ```

Question 29

dispersal rate in pleistocene?

Answer 29

``` • 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 ```

Question 30

dispersal ex starlings

Answer 30

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

Question 31

dispersal recent example cattle

Answer 31

• 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

Question 32

how did crickets in hawaii disperse

Answer 32

``` •:• 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 ```

Question 33

what is phylogeny biogeography? rules?

Answer 33

• 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

Question 34

vicariance and distribution?

Answer 34

• 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

Question 35

look at dispersal vs vicariance diagram

Answer 35

ok

Question 36

what are relic populations?

Answer 36

* 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.

Question 37

how can we explain relics?

Answer 37

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

Question 38

what is disjunct? ex?

Answer 38

• 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

Question 39

is glacial distribution vicariance

Answer 39

* 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

Question 40

look at land mass distribution. timeline?

Answer 40

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

Question 41

look at how gondwana broke up w madagascar

Answer 41

ok

Question 42

what explains gondwanan distributions

Answer 42

``` • 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

Question 43

what can lemurs show us about the land division

Answer 43

• 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

Question 44

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

Answer 44

ok

Question 45

Historical biogeographic analysis: Seychelles tiger chameleon describe

Answer 45

• 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

Question 46

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

Answer 46

• Mostly southern contient distribution Study in 2021 dispersal or vicariance

Question 47

ratite birds - dispersal theory

Answer 47

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

Question 48

if vicariance ratite birds

Answer 48

``` 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 ```

Question 49

ratite birds - which theory is correct?

Answer 49

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