Evolutionary Ecology I-III

How do you quantify/model LH strategies

- life history diagrams used to build MPMs, IPMs, integrated pop model,

Birds- LH changes in island forms

-Island forms invest more in parental care and offspring quality than mainland counterparts - Lower fecundity- fewer eggs/clutch - slower chick growth - slower LH in general

Eco-evolutionary change + example

A species evolving in response to a change in ecology- e.g. Biston bistularia on lichen-covered vs lichen-free bark

Good evidence for necessity of congruent timescales of eco-evo change

Alewives

Main question in eco-evo field

Main question: how pervasive are they, how do we convincingly demonstrate they are occurring, how close to proving they exist can we get

Broader niche width

· Scott et al. (2003) Foraging height and substrate comparison across 5 mainland & 5 island sites for silvereyes (birds) · Island populations show a significantly greater diversity of foraging behaviours than their mainland counterparts · On the mainland they forage v high in the trees and on islands they forage on the ground

Are herbicides a good system for studying eco-evo feedbacks- why is it so difficult to close the loop (Travis et al. 2014 paper)

- Changed extinction and invasion dynamics in this system could affect a lot of species and increased use of herbicide may produce a system where eco-evo feedbacks are generated- however only limited evidence for this - 'Closing the loop' requires a lot of data, as outlined by Travis et al. 2014- just observational data is not enough

Tests for why small--> large morphology on islands

- One idea is that under conditions of low interspecific competition and low predation, spare niches can be accessed with little risk --> removal of interspecific competition results in niche expansions - Larger bodied individuals have more access to a wider range of resources- produces a pop of large-bodied generalists - However, looking at a pop and seeing everyone is doing a bit of everything does not mean it is generalist 9see diagram)- Silvereye example (Heron island) individuals use a narrower range of foraging substrate and foraging height diversity than expected - Might not be about loss of interspecific but rather infraspecific comp, where high density pop results in competition and aggressive interactions, where being bigger is better - We cannot assume that the obvious or most intuitive change to biotic interactions underlies a component of island rule

Island rule

- Tendency to display evolution towards medium body size in insular settings - general across many types of taxa, has been demonstrated in mammals, amphibians, birds, dinosaurs, insects , fish, molluscs - strength of relationship varies across organisms - are there biases to how we assess the island rule? - there is likely ascertainment bias, perhaps some patterns are overly weighted by gigantism and dwarfism - likely not ubiquitous and upheld for some taxa more than others

Why does reproduction begin at larger sizes in nature than the ESS predicted by an IPM? (in a perennial semelparous species)

- We haven't included environmental stochasticity in our model- probability of survival is not only affected by size but also environmental quality - Once taken into account, the flowering treshold ESS is a lot closer to observed value

Cole's paradox

- When is it advantageous to reproduce multiple times throughout the lifetime of an organism vs just once? - For an annual species, the absolute gain in intrinsic pop growth which could be achieved by changing to perennial reproductive habit would be exactly equivalent to adding one individual to the average litter size - · At one point is it worth being iteroparous- why not just put all the resources into one more individual, only takes one individual to keep pop growth rate equivalent - Why not put all your resources into reproduction? - for semelparous to have the same pop growth rate as iteroparous only one extra individual needed - semelparity vs iteroparity is a continuum

Predictions of i.i.d. vs temporally autocorrelated enviornments for LH strategies that win out

- When you calculate the sensitivity of stochastic growth rate of a species to changes in positive autocorrelation in good v bad years, - it emerges that contrary to iid models, it is short-lives species that are more vulnerable- contrary to LH predictions

Eco-evo lecture points (4)

- what are eco-evo feedbacks - necessary conditions -anthropogenic situations: alewives and fertiliser - natural systems: sticklebacks and guppies

Demographic buffering hypothesis (and lability)

-Species that buffer against environmental stochasticity do so by constraining the temporal variation of vital rates that have high sensitivity o There is also evidence of the opposite strategy- demographic lability hypothesis o Predicts that species maximise fitness by doing the opposite of buffering- allowing vital rates with higher sensitivity to vary the most and constrain variation of rates with low input o This doesn't work for any species as it requires close tracking of how investment into given vital rates are synchronised with resource availability (temp, precipitation) changes through the environment

Morphology changes- island syndrome

1. Birds- reduced dispersal and graviportal form (dodo short squat arrangement) - smaller flight muscles and longer legs -mostly explained by raptor species richness and native mammal predator presence 2. Mammals: 'low gear' locomotion - short and stout metapodials - also decreasing in size to conform to island rule - slow, powerful locomotion 3. Birds: Plumage brightness and dimorphism - Reduced signal intensity and complexity in island birds -Could be due to relaxation of species recognition or some trade-off between other LH traits e.g. parental care , less stringent

What features of systems cause eco-evo feedbacks? (3)

1. Species with strong effect of phenotype on environment - different phenotypes have different effects on ecological variables e.g. species that greatly modify their own or other species' ecologies: Keystone species, niche construction and ecosystem engineers, habitat modification, changing nutrient cycling, consumption of resources NOTE: ecological context is important- high diversity vs low diversity communities and different abiotic environment 2. Strong effect of environment phenotype a. Ecological variables generate large selection coefficient on different phenotypes b. So we need genetic variation and trait heritability c. Factors that might constrain a pop from responding to niche construction/ecosystem engineering are the same factors that constrain adaptive evolution in general i. Genetic constraints , lack of variation, low heritability of traits under selection ii. Demographic, ecological constraints iii. Genetic drift or gene flow swamping strong selection iv. Antagonistic selection 3. Eco-evo change must happen on congruent timescales (whether both occur rapidly or slow)- discontinuity likely one of the disruptions to completing feedbacks when we don't see them

Physiological change

Birds & Bats: reduced BMR · Island, esp. small ones, due to restricted resource base + variable environment + absence of predators · Minimise energy expenditure by reducing BMR, increased cases of torpor

Evo-ecological change + example

Evolution of a species generates ecological change for itself or other species- e.g. a new mutation in a pest species that confers pesticide resistance impacts the ecology of primary producers

Herbicide effects on crop-associated communities

Iriart et al. 2000 - Herbicide use has strong direct and indirect effects on phenotypes and community composition - Sublethal exposure via particle drift and run-off - Herbicides are designed to produce over 90% death in target species, hence very strong selection pressure Non-target above ground: Direct effects: death, impaired navigation of pollinators Indirect: Plant community shifts, reduce dietary variation or availability of resources Target-plants Direct plastic and genetic effects: growth, reproductive traits and root morphology, reduced genetic diversity, herbicide resistance Indirect effects on plant community: local extinction, abundance changes, expansion of resistance species which impact plant-pollinator, plant-plant interactions and rhizobia mutualisms Non-target below ground - Reduce diversity and shift composition and functions of soil microbe communities - Short term decrease in colonization of plants by fungi, resistance in rhizobia strains

Anthropogenic changes that humans have imposed on islands

Island syndrome: an evolutionary trap? - Island species are over-represented in extinctions - 95% of terrestrial bird and mammal extinctions since 1500 are island species - Predators and disease major cause - Adapted to environment they were in but too far down evolutionary trajectory to cope with sudden and massive changes when humans arrived e.g. 1. Hawaiian archipelago - Domestic dog, pig and pacific rat introduced around 800 years ago - European arrival (1778) introduced more- e.g. rats, cats, sheep, goat, cattle - · Waves of extinction following both arrivals and all the declines in populations particularly from diseases are still being felt but some species are responding - Some species responding to reintroduction of predators (Oahu, Hawaii) - · Nest height increased by 50% over a 16 year period in response to non-native black rat predation · Thought to be a continuation of a shift started decades ago · Not a learned behaviour (individuals followed) it is an evolutionary response since individuals are not raising their nests each time · Evolving behavioural life history traits that might buffer them from the increased effects of predation and are responding to a changed biotic interaction 2. Tolerance to malaria infection- seen a response to disease threat in experimentally infected Amakihi - lowland birds show increased tolerance to infection

What are the broad but consistent ways in which island communities differ from mainlands

Islands: 3 Ds depauperate, disharmonic, & density- inflated communities • Depauperate: lower number of species overall o Function of area- serves as a proxy for how much heterogeneity on the island (and limits on habitat heterogeneity) & isolation o Island Biogeography Theory (MacArthur and Wilson 1968) • Disharmonic o Some functional groups particularly under- or unrepresented o Predators & parasites on the most remote islands species evolved free from parasites and predators in some cases • Density-inflated o Higher population densities than similar sized area of mainland, loads of species never get there in the first place o In some cases, total densities of multiple species on islands within a guild may exceed that of many more species on mainland - density compensation

Natural examples: Three-spine stickleback

Niche construction - allopatric speciation- generalist form -sympatric- creates bethnic and limnetic forms with different morphology and LH, generalist is intermediate - when started in same mesocosm with same prey, they change the environment and notable change littoral invertebrates, open water prey and light spectra Potential for evolutionary feedback - Light spectra change changes water colour and has visual impact which affects predator-prey dynamics and potentially sexual selection

Natural examples: Guppies

Trinidadian Guppies- Reznick and Travis (2019) review, have been studying for several decades Research approaches · Natural populations- replicated streams with and without predators · Experimental introductions in natural systems · Wild guppy demography: capture-mark-remark · Mesocosm experiments- semi-natural, situated in field conditions, but manipulations possible · Lab experiments-remove environmental variation - Nice set-up for studying eco-evo feedbacks 3 questions to prove eco-evo feedbacks 1. Do guppies affect their ecosystem in a manner that alters selection on guppies? 2. Do guppies evolve in response to their impact on the ecosystem?- those traits that change change expected to be due to reduced predation- changes that lag are eco-evo changes that occur due to changes in density and hence guppy impact on own ecosystem 3. Does guppy evolution, in turn, affect aspects of their ecosystem?

Bet-hedging

iteroparity as "insurance" against environmental uncertainty - imagine two annual semelparous species- one has all three offspring at once and one does not recruit a given proportion immediately but it remains dormant o However, under drought (environmental stochasticity) a bet-hedging strategy is more beneficial and will win out

Key assumptions of cole's model that might not always hold true

o No costs of reproduction- e.g. immortality o Juveniles are not fragile- in most wildlife pops they are o Lack of stage-specific density-dependence - in reality density-dependence is pervasive across ecological systems

Opportunities for anthropogenically driven eco-evo feedbacks

· Human modifications may produce strong selective pressures · Herbicide/pesticide use · Wildlife and fisheries extraction · Invasive species · Pollution · Climate change · Re-introductions, translocation and population supplementation

Behavioural naivité

· Not only in birds · Island macropods- loss of group size effects; forage more and less vigilant as the group size increases · If there are more predators there's a safety in numbers · Cumulative vigilance will protect the group · If there's reduced predation, these effects reduce altogether · Island lizards (66 species): · In lizards Flight initiation distance (FID) decreases with island isolation (distance to mainland) - how close you can get before they flee · Demonstration of island tameness in lizards

Define eco-evo dynamics

· Reciprocal interactions between the ecology of populations, communities and ecosystems and the evolution of organismal traits · When an organism alters some feature of its environment (biotic or abiotic) and changes the nature of selection it experiences - This in turn has causes evolution/ genetic response in the organism which further changes the environment etc. - Eco-evolutionary and evo-ecological change must occur simultaneously

Recurring selective changes (4)

· Reduced interspecific competition : wider niche; higher densities · Reduced suite of parasites/predators: behavioural naiveté; flightlessness, increased survival' low gear locomotion and graviportal phenotypes · Increase intraspecific competition: reduced territorial and aggression · Reduced need/advantage for dispersal: rounded wings (lower long distance flight capacity) ; flightlessness

Effects of herbicide resistance on interactions - creating the feedback

· Resistance genes directly affect interactions o Metabolic changes in resistant plants affect their quality in interspecific interactions or via trade-offs with other traits o Examples of resistant plants: - Weaker competitors - Increased susceptibility to herbivorous insects - Higher mortality from rust · Correlated changes of herbicide-resistant plants o Changes in reproductive timings could cause phenological mismatches with pollinators

Lecture: The evolution of LH strategy in changing environments

· Semelparity vs iteroparity- how can environmental stochasticity create a benefit to iteroparity o Example: Cohen, 1966 · Bet- hedging · Perennial semelparous species and environmental stochasticity in IPM/ ESS predictions o Example: Carduus nutans · Buffering vs tracking environmental stochaasticity o Example: Two papers · Predictions of iid vs temporally autocorrelated environments

Island lecture key points

• Islands versus continents (islands result in these extreme forms) • Components of the island syndrome • Examples from different taxa (incl controversies) • Identifying processes underlying patterns (changed biotic interactions) • Anthropogenic changes to island biotas (islands are not the refuges that they once were so how are islands responding to these new selective pressures)

Change in dominant form of biotic interactions on islands and resultant main threat

• Mainland: interspecific competition; predation; parasitism • Island: intraspecific competition (predation and parasitism are negated almost entirely) • Relaxation of some selection pressures (predation, parasitism etc) and introduction of different selection pressures e.g. primary cause of death shifts from predation to starvation • Bc of a high intraspecific comp on the island the threat is starvation- shift in primary cause of death on a pop level • Evolution of traits involved in the detection, acquisition, and utilisation of resources