BIOL214 Ecology - james Flashcards
Whats a Life history strategy?
asks questions why?
attempt to explain diversity we see in nature, through natural selection and why its come to be
Characteristics of an organism that then dictate their ability to maintain fitness in an environment (adaption)
allocating resources to what? growth, reproduction, maintenance
but accounts for trade offs when looking at traits
definition
pattern of allocation of resources for maintence, growth and reprodution.
what does life history theory suggest?
attempts to explain the diversity and mechanisms which natural selection has chosen to shape life history traits.
life history traits:
reproductive
-number of offspirng (ocean sunfish)
-timing of reproduction- careful in reproduction or whenever (mass coral spawning)
-sex ratio of offspring- investing more in male or female
(red campion has male and female parts)
life history traits:
Growth related traits
-Size at birth/ size at maturity
(blue whale largest newborn)
-Growth rates (catepillars growth 2-3mm to 30-40mm in weeks)
life history traits:
mortality related traits
-lifespan- grows slowly but last a long time bristlecone pine 4.5k yrs
-mortality schedule- when is a good time to die?
mayfly live most of life as a larvae and live as a few days as adults just to reproducing stage
objectives:
give examples of range of life history stratergies in nature
explain how natural selection, resource allocation and trade offs give rise to variety of life history strategies
how to group organisms based on their life history
Example pieris butterflies
large white and small white
differ in size
both like cabbage family (brassicase family)
2 different life history strategies
small lays 1 egg
and large lays many (gregarious)
small has more subtle markings and large has bright marks and stay together
why?
Large: takes up cabbage plant defences (mustard oils) accumilate in body and thus noxious to predators.
small: doesnt accumilate defences as well so needs to hide.
Darwinian fitness
lifetime reproductive success
selection for traits that equate to optimum darwinian fitness (reproductive success)
example
ocean sunfish:
lives in open ocean therefore doesnt interact with indivduals of other species has a long life so it has a higher chance of encountering others.
Produces high number of eggs to max fertilisation.
limits to optimising fitness
darwinian demon
https://pubmed.ncbi.nlm.nih.gov/24674028/
why is great duckweed a close comparsion?
unbeatable in nature
organism that commences reproduction almost immediately after birth, has a maximum fitness, and lives forever
individual plants do die but because its clonal then the og does exist (lineage)
Great duckweed-
A quantitative analysis (log-log bivariate plot of annual growth in dry biomass versus standing dry body mass of various green algae and land plants) revealed that duckweeds are thus far the most rapidly growing angiosperms in proportion to their body mass. In light of this finding, we discuss the disposable soma and metabolic optimising theories, summarise evidence for and against the proposition that the Lemnoideae (family Araceae) reflect an example of reductive evolution, and argue that, under real-world conditions (environmental constraints and other limitations), ‘Darwin-Wallace Demons’ cannot exist, although the concept remains useful in much the same way that the Hardy-Weinberg law does.
Importance of evolutionary traits and trade offs
whats happened in the past can limit what you can access now.
organsims trying to max success against these constraints, constraint examples:
evolutionary and phylogentic constraints- has evovled a certain way and therefore is stuck in its niche
physical and developmental constraints) allometric constraints-
you cant have a massive body and tiny legs
resource allocation trade offs
(in and between gen)
if parent has had good food and water hten so will the offspring
biotic pressure- other organisms can get in the way
Allometry
is the relation between the size of an organism and aspects of its physiology, morphology, and life history.
Trade offs
a change in one trait might increase but could decrease focus on another trait thus decreasing fitness in another way
Widespread trade offs-
adult size vs offspring number
(walker et al)
shows a negative size between fertilty rate and body size. the bigger the mammal the less offspring.
reproductive allocation vs adult survival-
reproductive effort- allocation of time and resources put into said care
risk of adult mortality relative to juvinile mortailty
low risk- delayed reproductive effort
high risk- invest as much as pos
types of trade offs
-offspring number (quality vs quanitity)
-productive allocation vs adult survival
-reproductive allocation vs offspring survival
sunfish example (mola mola)
not much invested in each egg, chuck out lots of offspring tho
Why is it useful to group species by diversity traits?
-understand the evolution
-understand how they might respond to change
-understand why some species are doing well with human interference
What traits might contriubute to species success?
life history-
behavioural traits-
aggression
adaptability
genetic traits-
evolutionary potential
physiological traits-
metabolism of an organism
morphological traits-
particualr morphilogical traits
outward appearance (camoflage etc)
other
habitat niche
dispersal ability
stress tolerance
Using species LHT to determine what the future might hold
paper example)
https://onlinelibrary.wiley.com/doi/10.1111/ele.12493
Grouping life history strategies
r vs k
Ways of classifying organisms
r- rate in which population can increase (expanding rapidly) mouse
k- carrying capacity, max population (more stable population) elephant
fast slow continuem-
allocation of production vs allocation of surivual
A theory in population ecology that attempts to establish whether environmental conditions favor the maximization of r (the intrinsic rate of natural increase) or of K (the carrying capacity of the environment). When populations can expand without food reserves limiting their growth, then r selection is in control. When food reserves limit population size, K selection takes over, and increase in one genotype must be at the expense of another. Whereas r selection operates in ecological situations where food reserves fluctuate drastically, and species are favored that reproduce rapidly and produce large numbers of offspring. K selection operates in populations that are close to the environmental carrying capacity, and species are favored that reproduce slowly and generate a few offspring that are well adapted to a relatively stable environment
plant life history variaition
J.P Crime
Broadly group plants in this triangle
Give examples of the diverse range of life history strategies observed
in nature
Explain how natural selection, resource allocation and tradeoffs give rise to the
wide diversity of life history strategies.
Contrast the different schemes for grouping organisms based on life
history strategies and explain why such groupings are useful
Modifications of an organism’s
life cycle to maintain fitness in
particular environments
(adaptations)
Age at first reproductive event, Reproductive lifespan and ageing, Number and size of offspring
natural selection (darwinian fitness)
Selection for optimal combinations of life history traits that increase
Darwinian fitness
example- ocean sunfish
resource allocation- reproductive allocation vs offspring survival
example (mola, mola)
lots of offspring to aid survival chance, in open ocean.
trade offs-
Organisms aim to maximise reproductive success given certain constraints
if giving more to one thing will it effect another too much?
correlation between adult size vs offspring number (walker et al, 2008)
schemes of grouping organisms-(surviorship curves)
r vs k (pianka 1970) do enviromental conditions favour r or k specific species?
issues (resnick, 2002) - stability of the habitat (which part is the soil, the forest etc)
adaptive capacity- changing to enviromental stimuli (coat when cold)
migration- dispersal patterns and coloisation of new areas (pollen release)
now turned to age‐structured demographic models mortality patterns as the cause of life-history evolution
other scheme-
grimes life history triangle c, s, r
competitive, stress tolerant, ruderal,
issues (loehle 1988)
In summary, the triangular data representation
scheme distorts data, results in loss of information,
and generates overly restrictive assumptions about
strategic or environmental trade-offs.
grouping organisms by specific traits
fecundity- high vs low
survival- short or long lived
offspring size- large vs small
age at reproductive maturity- young vs old
Species interactions and community assembly (mutualistic interactions)
lo:
Use examples, to describe the key features of mutualistic
(positive) interactions between species
Use examples to argue that mutualistic
(positive) interactions
are important for community assembly
types of interactions
positive vs negative inteactions (is it pos, neg or neutral)
outcome can vary through time and space. One way in the summer another in the winter etc.
test through=experimental manipulation of interaction
positive examples:
pollination
coral reefs
photosynthesis
negative:
cateipillar feeding off plant
types of positive interaction
(symbiosis)
interspecfic interactions (different species)
mutualism- both species gain in fitness
commensalism- one benefits but one is neutral
Types of negative interaction
interspecifc and intraspecifc
competition
predatorism
parasistm
What are mutalisms?(+/+)
a long term, close associated interaction, some cant live without each other.
needs:
net benefits must exceed cost
each partner benefits
Obligate (essential) and falcultative (useful but non esstential)
example?
obligate example: Yucca moths and yucca plants have a reciprocal obligate relationship- the plants cannot make seeds without the yucca moth, and the moth larvae only reach maturity if they eat developing yucca seeds (Pellmyr 2003).
falcultative: specific birds seed disepersal through flight.
commensalisms (+/?)
eating at the same table
long term close associsation where one benefits the isnt effected in anyway
examples:
-sharks and remora/sucker fish. aid movement through the ocean.
-cattle egret
mutualism examples
symbiotic and protective
mycorzial fungi and plants (fungal network)
plants produce carbohydrates (photosynthesis products)
fungal hypae help plant take up nutrients from the soil
(arbsucular and ectomycorzial)
protective mutualism
ants and acacias
how do ants protect the acasis trees, against inverts and mammals
how to experimentally test mutalisms?
palmer and brody (2013)
ant/acacia
manipulated the number of ants on the 4 trees and recorded tree damage (smoked trees)
categories:
control
1/3 ants removed
2/3 removed
all ants removed
once removed can look at how other animals interact with the trees
(elephants, beetles etc)
how does the acacia benefit?
reduced herbivore damage
increased chance of survival
how to ants benefit?
place to live
nutrition from nectur from acacia
Ant plant mutualisms are generally important for protecting plants
against invertebrate herbivory ( Rosumek et al. 2009)
meta-analysis of lots of studies can compare statistically which benefits are most identified across studies.
error bars over dotted line- not significant
other protective mutualisms
(one organisum for another, food for protection
the effect of synbiont density in protective mutualisms
Drew (2021)
https://orcid.org/0000-0002-9604-1821
endophytes in grasses- fungi deter herbivores
We found that the effects of symbiont density on protection and cost are robust across ecological contexts. Density-function relationships did not vary with host type, symbiont localization or transmission mode, nor the method of density manipulation. Together, our results suggest symbiont density can be a key variable determining the costs and benefits of a protective interaction.
how do mutualisms effect how communities are assembled?
Direct effects on mutualisms on -keystone species which entire ecosystems then depend on
examples:
mangrove tree- rhizosphere, roots and other microorganisms- capture atmospheric nitrogen.
effects of mutualisms in reducing the impact of stressors
ant/acacia- enable trees to persist in areas that otherwise would not have trees
(palmer and brody, 2013)
Facillitation
McIntire & Fajardo (2014). Facilitation as a ubiquitous driver of biodiversity.
The New Phytologist.
https://doi.org/10.1111/nph.1247
one species providing another a habitat for it to live in
We show facilitation to be a ubiquitous driver of biodiversity by first noting that all species use resources and thus change the local biotic or abiotic conditions, altering the available multidimensional niches. This can cause a shift in local species composition, which can cause an increase in beta, and sometimes alpha, diversity. We show that these increases are ubiquitous across ecosystems. These positive effects on diversity occur via a broad host of disparate direct and indirect mechanisms. We identify and unify several of these facilitative mechanisms and discuss why it has been easy to underappreciate the importance of facilitation. We show that net positive effects have a long history of being considered ecologically or evolutionarily unstable, and we present recent evidence of its potential stability. Facilitation goes well beyond the common case of stress amelioration and it probably gains importance as community complexity increases. While biodiversity is, in part, created by species exploiting many niches, many niches are available to exploit only because species create them.
an example of facillitation can increase community diversity:
cushion plants facilitate
each cushion plant species- 11 sites the number of plant species in paried design of with and wothout cushion plants.
on average- more cushion plants more other plants.
is the cushion suffering a loss?
competition
not bothered
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2009.01579.x
NMDS ordination indicated that cushions generate species assemblages structurally different from those found in open areas.
mutualisms under climate change?
co-extinction net works
tree diseases:
-ash die back, mild wet winters causing perfect disease breeding ground.
- one of the most common trees in the UK.
Bascompte
et al. (2019). Mutualistic interactions reshuffle the effects of climate change on plants across the tree
of life. Scientific advances. https://doi.org/10.1126/sciadv.aav2539
Extinctions induced by climate change may trigger coextinction cascades—groups of species disappearing as a consequence of the extinction of species they depend on—thus driving many more species to extinction than originally predicted
negative interactions: competition
2 organisms using the same limited resource.
Inter specific and intraspecific
types of inter and intra specific competition
direct competition: fighting or stealing food
indirect competition: plants competitng for soil and light etc.
why is intraspecifc competiton important for determining growth rates in a species?
logistic growth curves:
species introduced=exponential population growth. As the carrying capacity (k) is reached the population growth rate starts to slow.
half of the K is the fastest rate of pop growth
exponential population growth occurs due to?
low intraspecific competition
competition is often density dependence
2 forms, negative density dependance.
as populations increase then indivudals do less well.
driven by increase of competition for resources but also predators and disease
posititve density dependance (allee effect)
individual fitness will increase the population size. (some groups benefit with more individuals around)
example: blood flukes flatworm
how do you measure the strength of competition in nature?
lab: can check how strong the effect of compeition is by removing or adding resources
field:uncontrolled background enviornment but can still add or takeaway
observation: monitor the change of population in time. No manipulation.
what to measure?
population fitness (growth)
competitive effect (suppress a neighnour) and response (ability to tolerate a neighbour)
Measuring community diversity
Simpson index
D or Di
Diversity measure-
species richness and eveness
Shannon wiener index
H or H
factors shaping overall
Sousa (1979)
Boulder experiment
small boulders expected to be moved more often then bigger ones by wave action. Intermediate size boulders which are moved around occasionly but not that often.
Measured the Force used to move a boulder. If a boulder is moved around constantly then dominated by green alga and barnacles. Red algae on intermediate and large.
2 dates in which they collected data
N= number of boulders checked in each force class
intermediate= has the optimised number of species.
disturbance ecology- effects of exploitative interactions
distinguish between different types of exploitative interactions
use examples to illistrate how these interactions can cause disturbance thus causing diversity.
an interaction where there one member benefits and the other exploited
types of predation
i=d
ii=b
iii=c
iiii=a
experimental test on different herbivores on grassland test
allan and crawley (2011)
looks at insect and molluscs exclusion and the interactions between them.
Using insectersides etc to create exclusion in fenced and unfenced areas and looked for 14 years exclusion in factorial design.
data showed:
describe the effect of insects and molluscs on plant species richness.
describe the effect of insects and molluscs on plant species richness.
species richness is greater when insects are present in grassland but reduces biomass, independent of molluscs.
Molluscs tend to have a slight negative effect on species richness and increase biomass overall.
the effect of molluscs are dependent when insects are present or absent, but biomass bigger overall.
outbreak of specialist herbivores:
Kunegel-Lion & Lewis (2020). Factors governing outbreak dynamics in a forest intensively managed for mountain pine beetle.
https://www.nature.com/articles/s41598-020-63388-8
outbreak of specalist herbivores
lodgepole pine vs mountain pile beetle.
*Endemic phase at the start:
a few beetles around that are attacking the old trees.
*Epidemic phase- go for healthier trees.
*peak infestation
*post-endemic phase- resistant trees remain and others die- run out of host material.
then other trees would thrive during this time
heterogeneous environments strike a balance between succession and disturbance
finding the intermediate
whats too much?
interactions between disturbance types: the effect of one type alone is different when in combination with another
examples:
https://academic.oup.com/bioscience/article/70/10/854/5901988
-degraded habitat being more susceptible to invasive species
-extreme climate and invasive species
mountain pine beetle:
large scale tree death
humans- salvage logging or new samplings. But they’re all the same age and once reaching maturity are attacked again by beetles and cycle contiues
