Lecture 13 Flashcards
(84 cards)
1
Q
What is Biogeography?
A
- Study of the geographic distributions of plants and animals
- Quantifying patterns of past and present distributions
- Understanding the causes of such distributions
2
Q
What is seen on geographic range maps for common and rare species?
A
Common= more dots on map Rare= fewer dots on map
3
Q
What determines which metric is used to measure a species geographic range?
A
Depends on how good the sampling is for a particular species will drive the choice for which metric is suitable
4
Q
What pattern is generally seen when graphing range sizes of lots of different species as a histogram?
A
Very few are widely distributed and most are range restricted
5
Q
What size range do most species have?
A
Majority of species have small geographic ranges
6
Q
What are potential causes behind the mechanisms structuring range size distributions?
A
- Speciation/Extinction dynamics
- Ecological effects- habitat specialization, physiological tolerances etc.
- Historical effects
7
Q
What is the physical factors to species geographic range limits?
A
- Barries to dispersal: mountains, coast, etc
- Temperature: some environments beyond physiological limits, others suboptimal
- Seasonality
- Moisture and precipitation
- Salinity
- Ocean currents
8
Q
What factors contribute to the species geographic range limits?
A
1) Physical
2) Absence of suitable habitats
3) Biotic interactions
4) Adaptation and gene flow
9
Q
What biotic factors contribute to species geographic range limits?
A
- Competition
- Predation
- Mutualisms
10
Q
How does local adaptation and gene flow contribute to species geographic range limits?
A
- Local adaptation of peripheral population over time should push range further out
- Gene flow from the center pulls range toward it
- These two forces reach equilibrium which sets the range
11
Q
What is Endemic?
A
occurring nowhere else; a species, genera, families etc. can be endemic to a site or county or region or continent
12
Q
What is Endemism?
A
species can be endemic to a location on different spatial scales and taxonomic levels
13
Q
What are the two ways to be endemic?
A
- originate in a place and never disperse
2. range collapse
14
Q
What is Cosmopolitanism?
A
widely distributed throughout the world
15
Q
How many species are naturally truly cosmopolitan?
A
Few species
16
Q
What are making many species cosmopolitan?
A
Human introductions
17
Q
What are Provinces?
A
Well defined regions w/ taxonomically distinctive faunas
18
Q
What are Provinces aka?
A
Biogeographic regions
19
Q
What proportion of species may be shared between two separate provinces?
A
May share only small proportion of species
20
Q
How are boundaries between provinces?
A
Generally sharp
21
Q
What do boundaries often coincide with? What may some boundaries be a result of?
A
- Major changes in environment
- Some may be results of historical processes
22
Q
What is the species-area relationships equation?
A
- Empirical relationship
S= cA^z -> Log(S)= log (c) + zLog(A)
S= # species, A= area, c= fitted constant, z= fitted parameter
23
Q
What is the species-area relationships used for?
A
Heavily used for designing reserves (areas that are protected)
24
Q
What is the Theory of Island Biogeography?
A
A model to explain variation in # species on different islands
25
What are habitat islands?
Pockets of natural habitat that are nestled in the built environment
26
What is the relationship between immigration and extinction?
Over time, immigration rate slows because species are arriving to the new islands but extinction rates increase because of more interactions and other factors; equilibrium is reached when both lines cross
27
What is the immigration rate for near and far islands?
```
Near= high immigration rate
Far= low immigration rate bc it is more difficult to get there
```
28
What is the extinction rate for small and large islands?
```
Small= high extinction rate bc smaller areas has less species
Large= low extinction rate bc larger area can support more species
```
29
Which has the highest # of species? Lowest?
Near large islands- highest # species
| Far small islands- lowest # species
30
What are the 3 assumptions of why there is a continuous turnover of species under the Theory of Island Biogeography?
1. Biotas are in equilibrium
2. Immigration and extinction are independent processes
3. No speciation on islands (only about species coming from somewhere else, not species that evolve on a particular island)
31
What is an alpha diversity?
Small scale- # species within a sample
32
What is a Beta diversity?
Medium scale- extra species gained by combining multiple samples
33
What is the Beta diversity equation?
```
B= S/(a^) -1
S= total # species
a^= average # within a sample
```
34
What does the Beta diversity tell you?
How fast species are turning over as you sample one area to many different areas
35
What is gamma diversity?
Large scale- all species present in a region or in all samples
36
What is Type 1 relationship between local-regional diversity?
As regional species increase so does local species; there's a positive relationship
37
What is Type 2 relationship between local-regional diversity?
As regional species increase, local species do too but then reaches an asymptote
38
What does Type 1 relationship suggest about large scale processes?
Suggests that large scale processes are more important; no saturation
39
What are large scale processes mainly?
Mainly historical- speciation, extinction, climatic trends, etc.
40
What does Type 2 relationship suggests about communities?
Suggests that communities are saturated and local process are of primary importance
41
What are local processes?
Small scale ecological interactions such as competition for space and/or resources
42
What type of relationship is seen for Lake Fish in N. America?
Type 1- no asymptote observed, positive relationship between local and regional species
43
What is Macroecology?
focuses on large scale ecological patterns
44
What is the goal of Macroecology?
to understand processes underlying major biodiversity patterns- species richness, body size, abundance, geographic range, food web structures, etc.
45
What is Latitudinal diversity gradient?
Species richness decreases rapidly from the equator to the poles
46
Where is latitudinal diversity gradient common?
Very common pattern in both marine and terrestrial biotas
47
What might latitudinal diversity gradient be more of?
Might be more of a large eukaryotic phenomenon than microbes
48
How long has the pattern of latitudinal diversity gradient be around for?
Long time, about 145 million years ago
49
What is the general cause as to why there are so many species in the tropics?
The general cause remains poorly understood
50
What are the different processes that interact to produce the trend of latitudinal diversity gradient?
1. Ecological
| 2. Evolutionary
51
What is the ecological process?
- Density-dependent mortality
| - Species-energy hypothesis
52
What do density-dependent mortality apply to? Species-energy hypothesis?
- Applies to plants
| - Demonstrated in both plants and animals
53
What is hypothesis for evolutionary process?
- Longer time
| - Cradle or museum
54
What is the longer time hypothesis for evolutionary?
The idea that tropics have been around a lot longer than higher latitudes because of climate. When the climate decreases-> high latitudes take a bigger hit
55
What is the cradle hypothesis? Museum?
Cradle- increase speciation rate
| Museum- decreases extinction rate
56
What does it mean that seedling recruitment is often negatively density-dependent?
High species density= lower seedling recruitment of that species
57
What does negatively density-dependent allow? Why?
Can allow many species to co-exist because longer time to recruit seedling from the high species density
58
What is the density-dependent mortality of seedlings due to?
Due to species-specific predators or pathogens
59
What does the slope have to be to be negative density dependence?
Less than 1
60
Where is density-dependent mortality mostly observed in?
Southern hemispheres more than Northern hemispheres
61
What is the species-energy hypothesis?
Species richness of an area is a direct function of available energy
62
What is the trend seen in species-energy hypothesis?
Areas with higher energy availability seem to hold more species
63
How understood are the causes of the species-energy hypothesis?
The causes of this relationship remain poorly understood
64
What is the model for converting energy to diversity?
More energy-> more biomass-> more individuals-> more species w/variable population size
65
What are the problems with the ""more individuals" model?
- For plants: increased biomass may not translate into more individuals
- Relationship b/t biomass and individuals and species richness is not well known even for animals
- It is strictly based on present-day conditions- ignores historical processes such as speciation/extinction
66
What are the evolutionary explanations of LDG?
1. Age and climatic stability of the tropics
| 2. Changes in rates of speciation and/or extinction w/ latitude
67
What is the trend we see over time in the tropics and extra tropics?
Speciation starts in the tropics but over time tropical taxa extend their ranges into high latitudes
68
Why do we need to better understand the causes for latitudinal diversity gradient?
- We cannot predict the consequences of the declines
- In order to formulate management strategies
- Relevant for predicting biotic consequences of climate change
69
What is seen in body size distributions?
All scales are pretty sparse (small)
70
What is the size of most species?
Small
71
Is the smallest size the most common?
No
72
What is the distribution of the size-frequency?
Modal (tend to have peaks) with the mode normally towards smaller size
73
What is the modal size of mammals?
100 g
74
What is SFDs?
Size frequency distributions
75
How are the size ranges set?
By functional and/or physiological constraints- ex: surface/volume ratio for insects
76
What factors control the distribution of sizes within the range?
- Energetic model
- Fractal dimension of habitat
- Speciation/extinction rates
77
What is the energetic model hypothesis of body size distributions?
Body size distributions are set by energetic requirements of species
78
What is the hypothesis for smallest and large individuals under the energetic model of body size distributions?
- Smallest individuals are efficient in converting resources into reproductive effort, but are limited by rate of resource acquiring
- Large individuals are better at acquiring resources but they can produce fewer offspring
79
Where should the modal size be?
Where reproductive power is maximized
80
What are the shapes of SFDs dependent on?
Geographic scale
81
What does the energetic model only hold for?
For entire groups or continents
82
Why does SFDs vary with spatial scale?
Interspecific competition can lead to flat distributions- competitive exclusion can prevent similar-sized species from coexisting
83
Why do small species have a high spatial turnover?
Because small species are more specialized
84
Why do large species have less spatial turnover?
Because they have larger distributions
