Chapter 13: Species interactions, population dynamics, and natural selection

Question 1

List population interactions between individuals of two species?

Answer 1

1. neutral
2. mutualistic
3. commensalism
4. competition
5. amensalism
6. predation
7. parasitism
8. parasatoidism

Question 2

Population interactions between individuals of two species:

- Neutral?

Answer 2

• species a and species b do not harm or benefit each other..they are just occurring at the same place and time

Question 3

Population interactions between individuals of two species:

- Mutualism?

Answer 3

• both species benefit from having the other there

Question 4

Population interactions between individuals of two species:

- Commensalism?

Answer 4

-one species benefits but the other does not BUT the other species is not harmed

Question 5

Population interactions between individuals of two species:

- competition?

Answer 5

• negative for both species…competing for a resource..limiting the resource for both species

Question 6

Population interactions between individuals of two species:

- Amensalism?

Answer 6

• the opposite of commensalism..interaction between the species is having a negative impact on one and neutral for the other

Question 7

Population interactions between individuals of two species:

- Predation?

Answer 7

• positive(predator) and negative (prey dies)

Question 8

Population interactions between individuals of two species:

- parasitism ?

Answer 8

• host is not benefiting form the interaction…parasite benefiting

Question 9

Population interactions between individuals of two species:

- parasatoidism?

Answer 9

• positive for the parastoid but not the host

* *attached to a host not in the host

Question 10

13. 2 Species interactions influence population dynamics:

- interactions with other species alter what?

Answer 10

• birth and death rats of populations
  ex: if a predator is preying on other species..it is gaining nutrients etc making it more fit..prey is not mating…etc it died

Question 11

13. 3 Species interactions as agents of natural selection:

- Phenotypic variations among individuals affect?

Answer 11

• nature and degree of interactions
• these phenotypic differences in the degree of interaction may influence fitness, resulting in natural selection
• *some interactions are both physiological and behavioural but ALL influenced by phenotypes

Question 12

13. 3 Species interactions as agents of natural selection:

- do interactions affect all individuals in a population?

Answer 12

• no

Question 13

Coevolution?

Answer 13

• process of reciprocal evolutionary change through natural selection
• adaptation to another species can occur to thwart adaptive changes (e.g. predator-prey arms race) or reinforce mutually beneficial effect

Question 14

Describe the coevolution example with the hummingbird and plants?

Answer 14

• mutual relationship
• humming bird eats nectar…if a plant produces more nectar they will preferentially feed on that plant. As this plat starts t get bigger it has more nectar available and the plant wants this because the humming bird is cross pollinating via increasing dispersal
• *As the flower gets longer and more nectar the hummingbird wants to feed more so its beak size adapts….and it gets larger and becomes favoured.

Question 15

As the hummingbird and flower coevolve to each other what happens in terms of specialization ?

Answer 15

• they become highly specialized for each other…..limiting the amount of pollinators that can come and pollinate so if one of these species was to be lost the other would follow as well. (food source for one and reproduction for the other)
  therefore increased specialization = increased risk of extinction

Question 16

Species interactions can vary across geographic landscapes:

-Species with wide geographic distributions likely to encounter?

Answer 16

• many biotic interactions

Question 17

Species interactions can vary across geographic landscapes:

- Changes in nature of biotic interactions across geographic range can result in?

Answer 17

• different selective pressures and adaptations

Question 18

Species interactions can vary across geographic landscapes:

- can result in what differences?

Answer 18

• genetic differences among local populations

Question 19

Species interactions can vary across geographic landscapes:

- wide distributions?

Answer 19

• encounter a lot of species…lots of competition …you evoke to minimize that competition
• bc of these interactions with other species you are living with you can evolve different traits to help maximize your fitness within those competitive interactions over time through natural selection and evolution can result in genetic differences in local populations

Question 20

Species interactions can vary across geographic landscapes:
- wide distribution
L> just because there are a few genetic difference over time between two groups of organisms that are the same species does this make them completely new species?

Answer 20

• no

- you can still occupy the same area and breed but over time these differences become greater and the species diverge

Question 21

Species interactions can vary across geographic landscapes:

- are hybrids true species?

Answer 21

• not true species since they cannot produce viable young

Question 22

Explain the cost-benefit curves for individual plants with and without mycorrhizal fungi associated with the root system across a gradient of soil nutrient concentration.

Answer 22

• Mycorrhizal fungi provide increased access to soil nutrient shut cost the plant carbon resources.
  (a) At low soil nutrient concentrations, the presence of the fungi increases growth rate and plant size compared to plants without fungi. (b) As nutrient availability in the soil increases, the presence of fungi switch from a net benefit to a net cost. The carbon cost to the plant in supporting the fungi yields little benefit but costs the plant carbon that otherwise could be used for growth. Under high soil nutrient concentration the plants without fungi have a higher growth rate and size.

Question 23

Species interactions can be ?

Answer 23

diffuse

*most interactions involve >2 species

Question 24

Species interactions can be diffuse:

- what can occur between many species that use overlapping resources?

Answer 24

• competition

Question 25

Species interactions can be diffuse: | -diffuse __ can occur as well.

Answer 25

coevolution * plants and pollinators * ex: three bugs coevolve with three different flowers....they have diffuse interactions bc they are all intreating with the three flowers..they have a diffuse relationship even though they are not directly interacting with each other.

Question 26

13. 6 The concept of a niche: | - niche?

Answer 26

- functional role of a species in a community. Includes range of conditions and resources under which it can survive and reproduce * *what that species is doing in the community and its interactions can have an impact on all other species

Question 27

13. 6 The concept of a niche: | - a species niche is?

Answer 27

multidimensional

Question 28

13. 6 The concept of a niche: | - A species niche is multidimensional??

Answer 28

species may overlap in one dimension of the niche but not another - many resources and environmental factors graph ex: y= humidity, x= temperature ..z= foodsize **its okay if you are competing for one resource but when multiple are involved things will not do well..

Question 29

Species interactions influence species' niche: | - two types of niches?

Answer 29

- fundamental niche | - realized niche

Question 30

Species interactions influence species' niche: | - fundamental niche?

Answer 30

- physiological niche - derivative of the ecological niche as a whole..description of all the set of environmental conditions that species needs to persist. Interactions like competition can restrict the environment one species can permit, (competition with other species can determine whether or not you can live in a particular niche_

Question 31

Species interactions influence species' niche: | -Realized niche?

Answer 31

- portion species actually exploits in the presence of species interactions

Question 32

Species interactions influence species' niche: | - a portion of a fundamental niche a species uses is a result of the ?

Answer 32

interactions it has with other species (realized niche) | *if you took those other species out the species the species you are looking at may use more resources/different ones

Question 33

Species interactions influence species' niche: | - does a species use every resource available?

Answer 33

- no it will only use parts of the niche that maximize its survival and reproductive fitness. Those are what it will compete most intensely for.

Question 34

Species interactions influence species' niche: | - cat tails example?

Answer 34

Distribution of two species of cattail (Typha latifolia and Typha angustifolia): (a) along a gradient of water depth; (b) grown separately in an experiment; (c) growing together in natural populations. The response of the two species in the absence of competition (b) reflects their fundamental niche (physiological tolerances). The response of each species is altered by the presence of the other (c). They are forced to occupy only their realized niches.

Question 35

13. 7 Species Interactions Can Drive Adaptive Radiation: | - what is adaptive radiation?

Answer 35

- process in which one species gives rise to multiple species that exploit different features in the environment ex: finch birds in galapagos islands * ex: you have one species that reaches a place like an island for instance…all different niches that could be occupied so different phenotypes begin showing up so they can exploit slightly different niches…so over time you have this divergence of one species giving rise to multiple different species

Question 36

13. 7 Species Interactions Can Drive Adaptive Radiation: | - factors driving phenotypic divergence?

Answer 36

- resource competition - divergent adaptations to avoid predators ( different species with different phenotypes may do different things to combat predation)

Question 37

13. 7 Species Interactions Can Drive Adaptive Radiation: | - example: contrasting ecotypes of walking stick associated with two host plants

Answer 37

- adaptations to reduce predation - reproductive isolation not complete - -small insect -associated with two host plants -same species…still one species of walking stick but they exploit two different plants in the same area genetic results? why are they exploiting these twos afferent plant species…affect on genetic makeup? they’ve found that the plants differ really strikingly on foliage and how they are exploited by the walking sticks variation in phenotype traits has allowed the different walking sticks to lower competition…increasing populations some individuals are a little bit bigger and really good at exploiting one plant etc different ecotones if you switched the host plants on them…survival and reproductive success goes way down..they may not even survive precursor to the formation of two species diverging will happen in terms of genetics…what they look like and exploit over time this will potentially be confirmed