Biol 413 Pre MT Flashcards
Dispersal Hypothesis
Sea turtle example:
arrived recently
Some females strayed from natal beach and established nests on beach
Vicariance Hypothesis
Sea turtle example:
arrived a long time ago
turtles nested on beaches of adjacent slands - islands have been displaced by sea floor spreading
Time periods of biogeography
Exploration: 1700-1900
Integration: 1900 to 1960
Maturity: 1960 to present
Exploration
classified geographic regions based o biotas
recognized patterns in species diversity
Linnaeus
Father of binomial nomenclature and taxonomy
Believed in immutability of species
Taxa have centers of origin (ex. indo-west pacific is center of origin for marine fishes)
Geogrges-Louis Leclerc, Comte de Buffon
1) Earth must be older than biblical claim
2) taxa changes through time therefore must have a relationship with geology and biological histories of earth
1st law of biogeography
1st law of biogeography
Environmentally similar but isolate regions have distinct species assemblages
Alexander von Humboldt
Extended 1st law to plants and terrestrial animals
“floristic belts” - promoted the idea that plant distribution is determined by climate
first to note south america fitting with west africa
Charles Lyell
Principles of Geology
Stratagraphic layers and fossils suggest earth is changed through time and gradually
Uniformitarianism
Uniformitariamism
basic natural laws and processes have always acted on the earth and understanding present geological processes is key to understanding the past
Charles Darwin
Natural selection is key factor in the origin of species
Dispersalist
Dispersalist
Rare long-distance dispersal events establish isolated populations that ten differentiate
Extentionist
land bridges (now submerged) facilitated the extension of distributions between land masses
Phillip Sclater
made connection between low dispersal ability and ability to construct biota from current composition
biogeographic line
a geographic boundary that animals
(or plants) tend not to cross. Some lines are more
permeable that others, some taxa less constrained.
6 biogeographic regions
Nearctica (North America and parts of Mexico)
Palearctica (Eurasia)
Neotropical (tropical central America and S. America)
Aethiopica (Africa)
Indica (Indian subcontinent)
Australiana (Australia)
Alfred Wallace
Described observations on distribution, diversity, extinctions, diversity, etc.
Refined sclater’s regions
Wallace’s Line
which separates fauna of southeast Asian origin from those of Australian origin.
Bergmann’s Rule (1847):
Body size tends to increase with increasing latitude
Allen’s Rule (1878):
Species at higher latitudes tend to have shorter, smaller limbs
than those at lower latitudes.
Jordan’s Rule (1881):
Fish species / populations at higher latitudes have more and
smaller vertebrae than those from lower latitudes
Evolutionary Synthesis
Classical Mendelian genetics, theoretical population genetics, systematics,
and taxonomy unified into a comprehensive body of theory of evolutionary
change – how factors such as genetic drift, mutation, and natural selection
could drive evolutionary change
4 key developments after 1960:
1) Acceptance of continental drift + plate tectonics
2) Phylogenetic systematics: the basic philosophy of reconstructing the
historical and evolutionary relationships among taxa
3)Ecological biogeography: contemporary interactions and species
relationships are important in the determination of species range limits.
4)Technological advances allow old hypotheses to be tested rigorously
and expand the spatial scale of biogeographic inference: Computers,
Satellites and remote sensing, Geophysics, Geographical Information
Systems (GIS), Molecular biology technology
Phylogeny:
the evolutionary relationships between an ancestor taxa
and all its known descendant taxa
Phylogeography:
an approach to biogeography that studies the
geographic distributions of lineages within and among species
Changes in the crust are driven by two engines:
1) Energy stored in the earth’s core dissipates through the mantle and the crust shaping the earth’s crust
2) Energy from the sun strikes the earth’s surface and is absorbed and converted into heat
Spherical shape of the earth: heating
causes a latitudinal gradient of thermal radiation
Close the the equator the area of radiation and distance travelled is smaller so heat energy is maximized
Cooling effects of elevation
pressure and density of air decreases with altitude - with reduced pressure air expands and undergoes adiabatic cooling
Coriolis Effect:
the tendency for moving objects (e.g., wind and currents)
to veer clockwise in the NH and counterclockwise in the SH. We see this
effect easily between 0 and 30 degrees North and South latitude
Trade winds and westerlines
Trade winds: blow west to east at high latitudes
Westerlies blow: east to west at equator
Causes clockwise in Nhemisphere and counter in S hemisphere
Horse Latitudes:
warm, dry surface winds
“dry-out” the land and create most of our
great deserts near 30o
N and S latitude (e.g.,
Mojave, Sonoran, Sahara, Gobi, and Great
Sandy deserts).
-The land is cooler than ocean in these areas and as a result in the winter the warm air brings rainfall to the area. (opposite is true in summer)
Rain occurs where
the air is warm and rising: warm air is able to store more moisture… them more it rises the more saturated it gets until it will precipitate as rain or snow at its peak- and as it falls and cools down
Areas where the air is cooling and falling is dry air that is taking moisture from those areas (i.e. deserty areas)
The adiabatic lapse rate
is the rate at which air cools as it rises. This lapse rate
varies for many reasons, but generally, the lapse rate differs with and without
condensation
El Nino Southern Oscillation (ENSO)
period of weather change that occurs every 5-7 years due to the strengthening of the equatorial countercurrent (cause unknown). Increased rain (often 10x) in arid coastal regions of SA, and reduced coastal upwelling.
Geographic range
basic observational unit of biogeography, encompasses the
maximum geographic extent of occurrences of a taxon during part or all of its
life cycle.
Ways to describe distribution
Dot maps, outline maps, contour maps, seasonal range maps,
Way to quantify distributions
extent of occurrence
area of occupancy
Extent of occurrence
Uses polygon method:
may encapsulate areas that are uninhabited
Area of occupancy
using a grid ,
using geo-political boundaries
Challenges: outbreak times are usually much larger than regular times
-breeding/overwintering areas are much different
Growth rate per capita
r = b + i – d – e
r is the per capita rate of population growth
if r is positive = population increase
if r is negative = population decline
b and d are per capita birth and death rates,
respectively
i and e are per capita rates of immigration to and
emigration from other populations, respectively
Fundamental Niche:
total range of abiotic environmental conditions in which a
taxon can survive and reproduce
From Hutchinson (1957) the n-dimensional hypervolume (or multidimensional space) that describes the range of abiotic environmental conditions in which a taxon can survive and reproduce (each abiotic factor is a single dimension).
Ex: Eastern Phoebe and northern wintering range limit
Realized Niche
A subset of the fundamental niche comprising the actual
environmental conditions in which a taxon survives and reproduces in nature,
including biotic factors (competition, predation, mutualism, etc).
Caveats of the niche
Species may inhabit unfavourable areas or not be present in favourable areas (due to geographic barriers)
Sink-
Death rate > birth rate - depends on immigration to maintain population
Source
birth rate>death rate - migration keeps population in check
Metapopulation structure
when niche space is patchy, patches occupied intermittently
Metapopulation
: a population consisting of a set of subpopulations linked
by a cycle of alternating colonization and extinction (Levins 1970)
ex glanville fritillary
Disturbance
ex. andean high treeline - grasses set to fire
Determinants of distribution
Niche
Metapopulation structure
Disturbance
Biotic interactions
Biotic interactions
Direct competition (gray vs white breasted wood wrens) Diffuse competition Predation Mutualism Historical Factors
Diffuse competition:
the combined effect of competition with many other
species – one species is negatively affected by numerous other species that
collectively cause significant depletion of shared resources (MacArthur 1972).
(ex cavity nesters vs open cup nesters
Predation
Ex: Manu National Park, Peru predation
predation decreases with elevation
high species turnover = lots of range overlap
highest species turnover corresponds with highest predation rates
Mutualism
ex. clark’s nut cracker and white pine’s cones
clownfish and sea anemones
Note: Mutualism is not perfect predictor of distribution
historical factors
Ex. white suckers in fraser river but not columbia or skeena rivers.
Species of NA birds occupied certain areas during the regression of the glaciers
Animals differ ability to adapt due to:
evolutionary constraints
gene flow from center of range
trade offs
Evolutionary constraints
In order to adapt via natural selection you must display:
- Inheritance: Specifically replication with inherited traits.
- Variation: Namely, genetic variation within the population.
- Competition: Specifically, competition for survival and reproduction within the population.
Gene flow from center of range can be impeded by:
small populations and low genetic variation at the peripheries
and high gene flow coming from the center (ex: A is favoured at periphery but rare at center, therefore a will swamp and selection for A at the periphery)
Trade offs
ex. in stickle backs trade off between spines (predator defense) and fecundity (number of eggs)
western blue birds - less aggression in older and better established populations.
non aggressive, staying birds have higher fecundity than aggressive or dispersing birds
Biogeoclimatic zones, ecoregions, and biomes are defined by:
- precipitation
- humidity
- temperature
- soil characteristics
- microbial life
- flora
- fauna
Biomes
regions defined on the basis of distinct abiotic and biotic
characteristics involving climatic and soil conditions and assemblage of
plant and animal species.
Types of biomes
Tropical, temperate, desert, boreal, tundra
Aquatic biomes
Marine: photic and aphotic
Freshwater: Limnetic (includes Littoral), profundal (includes pelagic and benthic)
Lentic vs lotic
lentic still standing
lotic flowing
“individualistic” hypothesis, proposed by Gleason
species do not occur in definable communities
Inter dependance
Clements proposed that co-occurring species occur as definable units
…species within communities were interdependent and coevolved
Whittaker’s combination
Whittaker combines both individualistic and community-unit scenarios including biotic processes (also competitive interactions and species replacements
Succession
Primary succession: succession “from scratch”, i.e. from a place devoid of life
and the soil on which it depends. Imagine a volcano or glacier that destroys
all life, leaving bare rock or till.
Secondary succession: succession when the soil is left after a disturbance
(e.g., flood or fire). Also includes later stages of succession as communities
return to natural vegetation.
Species Concepts
morphological species concept
phylogenetic species concept
biological species concept
Morphological Species Concept:
a species is a morphologically
distinct group of individuals that has few or no intermediates when in
contact with other such clusters (Mallet 1995).
Issues? how to differentiate what is a species?
some species genetically different but morpho identical, some species have a lot of morpholigical diversity
ex. yarrow is very different along different elevations
Phylogenetic Species Concept:
a phylogenetic species is (1) a monophyletic
lineage, (2) derived through an evolutionary process of descent from an
ancestral lineage and (3) diagnosable through examination of character
state transformations (McKirktrick & Zink 1988; Cracraft 1989).
issues? which character traits to focus on ?
need to understand/know evolutionary history of species
benefits: can apply to sexual and asexual populations
Biological Species Concept (BSC):
species are groups of interbreeding
natural populations that are reproductively isolated from other groups
(Mayr 1942, 1995). Most widely held concept for species delineation
issues: actually vs potentially not interbreeding?
what about geographically isolated species?
fossils? asexual species?
Mechanisms that affect speciation
Physical isolation dispersal genetic drift natural selection sexual selection mutation karyotypic changes polyploidization hybridization
“Dobzhansky-Muller incompatatbilities”
as populations diverge different alleles may become fixed in each by natural selection or genetic drift
Allopatric speciation
evolution of reproductive isolation when in geographic isolation
- no sister species when no isolation possible
- sister species in to isolated populations
ex. phylogeny of albula
ex. range boundaries- bullock orile and baltimore oriole - across rockies?
Darwin’s Finches 3 steps to speciation
1) Colonization of archipelago
2) established allopatric populations
3) establishment of sympatry
Peripatric speciation
special type of allopatric speciation due to founder’s effect and high genetic drift
ex: coco’s island finch
Parapatric speciation
variable populations diverge along a selective gradient
Problems of sympartic speciation
1) divergent selection is counteracted by gene flow, solution: evolution of assortative mating or close linkage between reproductively isolated genes
2) coexistence instead of competition, solution: speciation is driven by ecological divergence
Criterion for selection sympatric speciation
1) Must be sister species
2) history of species must indicate allopatry unlikely
3) must be reproductively isolated
4) must be living in sympatry
Dispersal
The area where in individual reproduces or would reproduce if it survived to reproduction/found a mate
Migration is not dispersal
Migration: the spatially and temporally predictable movement of individuals bewteen breeding and foraging habitats
Vicariance
occurance of a barrier between a popluation that already existed causing it to differentiate into two different populations
Mechanisms of dispersal
Propagule
vagility
pagility
sweepstakes dispersal
Propagule
any part of an organism, individual of a population that can establish a new population
Vagility
ability to disperse actively
Pagility
passive dispersal where dispersal is from a force independant of individual
Sweepstakes dispersal
stochastic dispersal of a species and the creation of disjunct, remote or disharmonic biota
ex. green iguana on anguilla, from hurricane
Barriers
Physiological barriers
Physiological barriers
ex. temperature tolerance
like with puffins
high altitude species have a wider tolerance to temperature than tropical species
Corridor
a non selective dispersal route that allows individuals to move from one area to another
Filter
a selective dispersal route that only allows certain indivduals to cross from on region to another
Range expansion
jump dispersal
diffusive dispersal
Jump dispersal
dispersal over long distances of inhospitable habitat
results in discontinuous living ?
ex cattle egeret - colonize SA
Diffusive dispersal
ex. armadillo
movement into adjacent habitats
Evolution of Dispersal
Genetic basis of dispersal
Maintenance of dispersal potential
Establishment of new populations
Dispersal
higher in unstable environments
higher in conditionally-dependant dispersal (compared to vicariance)
Why dispersal?
unstable environments
colonization of new environments
reduction of inbreeding depression
reduces competition
Why philopatry?
increased familiarity with variable environments
returns locally adpated individuals to appropriate habitats
avoids cost of movement
