Lecture 7: What makes a species a successful invader?

Question 1

List three reasons some species are more successful invaders vs others

Answer 1

1. Some species are given more opportunities for dispersal (e.g. commercially important species)
2. Some species are better suited for human vector dispersal
3. Some species possess traits that make them better colonizers.

Question 2

Can we predict successful invaders base don their taxonomic affiliations?

Answer 2

• evidence says no to closely related species having similar invasion success
  ex:
• Round Goby vs Tubenose goby
  L> both in the same family and share some traits BUT tubenose is not as a successful invader. It has established, expanded but not as extensive as the round goby. Where as the round goby is the most invasive vert in the great lakes

Question 3

Contrast the European Sparrow vs Eurasian tree sparrow

Answer 3

• very closely related sparrows
• introduced at the same time
• euro house sparrow has done super well
• eurasian tree sparrow has a very large native range but small exotic range. It is now moving bc of climate change but this does not mean it will be as successful as the house sparrow

Question 4

Coyote vs Grey Wolf

Answer 4

• coyotes are native to the continent and do very well in human dominated landscapes
• grey wolves on the other hand are not doing as well esp in human dom areas.
• very similar to each other BUT so different
• could be differences in social structure and diet. Grey wolves eat ungulates, coyotes are scavengers BUT wolves have a social structure in packs, where as coyotes live on their own.n
• Packs mean they need a larger territory which is more obvious to humans
• SO key point: those with flexible diet and less rigid social structure can be more successful in a human dominated region

Question 5

Compare atlantic salmon vs brown trout

Answer 5

• Atlantic salmon populations have failed, whereas brown trout is one of the world’s most successful colonizers.
• • brown trout can tolerate poorer water quality conditions (low O for ex) vs salmon
• *otherwise closely related

Question 6

Compare Black rats and Brown rats

Answer 6

• euro ones have taken adv of human expansion

- other ones are on islands without many people

Question 7

Compare water hyacinth vs other congeners.

Answer 7

• it is one of the world’s most invasive aquatic plants
• it’s congeners have no invasion histories even though they are distributed worldwide by aquarium industry

**if opportunity is equal, trait differences might be why there are differences in invasion success

Question 8

For successful invasion to occur, a sp must be able to rapidly build a population from small numbers. Explain corresponding attributes for invasibility.

Answer 8

Contributing attribute:

• High r (intrinsic population growth):
• Asexual reproduction: if you do not need to wait for sexual maturity, reproduce through dormant stages, vegetatively etc this could allow a pop to grow from small numbers.

Question 9

For successful invasion to occur, a sp must be able to rapidly build a population from small numbers. Explain predictors for invasibility.

Answer 9

1. High Fecundity
   - high reproductivity output (ex lots of eggs through reproduction output event)
2. Short generation time
   - can generate a large population quickly bc not a long wait for sexual maturity.
3. Body size
   - small body sized organisms reproduce very quickly, reach maturity faster etc so it might be a predictor bc it is a proxy for little r when all other aspects are equal.

Question 10

Whats the deal with body size of animals introduced into britain.

Answer 10

• probability of establishment, log mean length increase together
• BUT this could be a bias
• we may just not notice small things as well
• bias 2: we intentionally establish larger organisms
• things we tend to like are usually larger

Question 11

Explain the Smalls rule of invasion.

Answer 11

• small bodied species are disproportionately absent from recorded invasions
  i.e. the recognition of invasion is inversely correlated with body size
  L> reason = their occurrence is more likely to be overlooked and their nonindgenous origin is less likely to be detected

Question 12

Explain the relationship btwn body size of insects introduced to britian

Answer 12

• larger ones are less likely to establish

* smaller ones can reproduce quickly

Question 13

Is there much of a difference in invasion success vs clutch size for birds introduced to Australia

Answer 13

• no
• not much of a difference for large and small clutch sizes and establishment
• not sig

Question 14

Relationship btwn invasion success and egg production of birds introduce to britain

Answer 14

• invasive sp produce more eggs

Question 15

Compare native and invasive cordgrass in california

Answer 15

• non native sp produce more pollen aka have a larger reproductivity capacity

Question 16

For successful invasion to occur, a sp must be able to adapt quickly to new habitats. Explain corresponding attributes for invasibility. + predictors

Answer 16

• generalist
  L> adapt to a broad range
• broad diet, being able to exploit many resources
• wide native range = bc it means if you exist across a wide range, at least within your sp there are varieties that can tolerate a broad range of climatic conditions
• broad physiological tolerance
• high genetic variability

Question 17

Explain the Niche breadth-invasion success hypothesis.

Answer 17

• generalist sp are better invaders than specialists, bc the former are more likely to adapt to find the resources they need and adapt to new environments

Question 18

Explain the predictors of the rich breadth invasion success hypothesis

Answer 18

• diversity of conditions in native habitat
• geographic or climatic range
• behavioural flexibility (ex predator avoidance )

Question 19

Explain the relationship btwn the home range size and a sp ability to be invasive.

Answer 19

• the larger the home range, the higher the probability

Question 20

What are three traits that separate invasive and non invasive pine sp.

Answer 20

1. length of juvenile period: those that take a longer time tend to be not as invasive
2. Interval btwn large seed crops: those that take a longer time btwn seed cries tend ti bit be as as invasive
3. Seed mass
   - those with larger seed mass seem to be less invasive

Question 21

Explain why natural plants have smaller genomes than their on invading relatives: a flow cytometric analysis of the Czech alien flora

Answer 21

• larger seed has more genetic material
• a lot of it doesn’t code for protein
• they need to reproduce this genetic material every time the cells of the seed are splitting
• ## this slows down the rate at which seeds are produced. THEREFORE smaller seeds with smaller genomes can be produced quirk r.

Question 22

Explain functional differences between native and alien species with a global scale comparison.

Answer 22

• comparison of co occurring native and non native sp:
• 15% higher leaf area (faster growth rates)
• 16% lower max height of adults (shorter time to reach reproductive age)
• 26% smaller individual seed weight (more seeds per reproductive effort).
• *traits of non native spp.

Question 23

For successful invasion to occur, a sp must be able to exploit anthropogenic and natural dispersal opportunities . Explain corresponding attributes for invasibility. + predictors

Answer 23

Attributes:

• possesses mech of rapid short distance dispersal
• commensal with humans

Predictor:
-past invasion history

Question 24

Whats the relationship between invasiveness and migratory behaviour in Eurasian birds?

Answer 24

• migration is not the same as dispersal
• dispersal is more random and maybe more important in young birds bc they could be pioneers leading others to a new satellite colony
• no correlation with migrants to invasion, going long distances to the same place every time will not give chance to invade new regions

Question 25

What is a common among introduced and established fish?

Answer 25

• the most popular tends to be more invasive
• introduced and established taxa are typically larger than others available in stores
• *free willy syndrome

Question 26

Compare growth rates of native and non native apple snails .

Answer 26

• invasive ones tend to grow quickly
• can reproduce faster and produce more offspring
• they also tend to eat more than others
  **resource consumption hypothesis
  L> more invasive sp consume more resources efficiently and quickly. Need to convert biomass to offspring more frequently