Types of co-evolution (Species Interactions)

• Predator-prey (Exploitation)
• Parasite - host (Exploitation)
• Mutualism
  • Facultative or obligate
  • In the shrimp example, it's facultative for the fish and obligate for the shrimp
• Competitors
  • Competing for the same resources
  • Example - threespine stickleback species pairs who differentiate to avoid competition

Examples

Well-being

• Bedbug / Wolbachia co-evolution
  • These Wolbachia bacteria provide vitamins to the bedbugs
  • By studying these, they developed new treatments for bedbugs

Conservation

• Speciation in coral reef studying?

Fig-wasp mutualism

• Ficus figs are actually inflorescences
• Complicated life cycle with wasps - obligate mutualism
  • Female wasps enter the fig to pollinate the female flowers and lays eggs
  • Later, the eggs hatch and the young leave, covered in pollen, to lay eggs in another cell
• Males are only suited for boring holes so the females can leave the figs, often have no wings
• Females are adapted to flying, burrowing into figs and laying eggs in the fig oocyte
• Parasitic element also - there are some paracitic wasps who use a long ovipositor to puncture the egg and lay from the outside without pollinating the fig
  • This parasite reduces fitness in both figs and pollinator wasp
    • Some species will predate on the pollinator wasps
• Figs balance their own reproductive success to try and avoid the parasites and encourage the pollinator wasps
  • Co-evolution: They may produce flowers at different style lengths... why??
  • Some will produce either all-male or all-female flowers... this somehow reduces parasitism?

Arms Race

• Red Queen Hypothesis
  • Must constantly adapt just in order to survive (stay in place)
• Sexual Conflict

Arms Race Example - Passiflora and Heliconius

• Passiflora flowers defend using certain chemical defenses against certain insects
• Heliconius butterflies eat these compounds, which they tolerate, but also use these to become toxic to predators

Structural changes

• Passiflora evolved very diverse leaf shapes and sizes
  • This makes it harder for butterflies to recognize the Passiflora as a host plant, since they rely on visual clues to decide where to lay their eggs
• Developed little structures that mimic eggs, to make the butterflies think the plant has already had eggs laid on it

Response

• Heliconius have evolved larger brains in order to distinguish shape and chemical profiles of plants

Ant protection

• Developed little non-floral glands that produce substances to attract ants, which will also defend against Heliconius or other predatory insects

Response

• Laying eggs on specific parts of the plants where the ants can't reach

Trichomes

• Tricohmes on some species - tiny hooks on the leaves that are defenses against larva by preventing them from walking on the leaf

Response

• When they were first studied (1970s), it seemed that the plant had won here, no insects can avoid this
• However, it was found that one Heliconius species charithonia could survive by eating the tips of the trichomes (2008)

Co-evolution at a local scale - evidence

• Some species use mimicry with their hosts such as this kind of butterfy which have larva that mimic Myrmica ant chemical signals so that they are raised by the ants
• They have very small amounts of overlap (at Åland)
  • Two species - rubra and ruginoidis
    • rubra ants have more diversity in chemical profiles between colonies, so the butterflies fail to infect (trick) it with their fake larva
    • ruginoides are more susceptible since their chemical profiles vary less

Geographical Mosaic Theory of Co-evolution

• Co-evolution is a spatially-structured process

Assumptions:

• Species are collections of distinct populations
• Interacting species differ in geogrpahic ranges
• Interactions differ between environments

Three sources of variations

• Geographic selection (e.g. differences in climate, temp, elevation)
  • Adaptation that is good in one env is negative in others
• Evolutionary coldspots vs Evolutionary Hot Spot
  • Hot Spot: Geographic location with a high rate of evolutionary change, such as a tropical area with high biodiversity, such as
• Trait remixing?

In fossil record:

Angiosperm and beetle co-evolution

• There is a correlation between beetle diversity following divergences in angiosperm diversity
• Exponential increase in angiosperms in cretaceous led to massive diversification of beetles

Gastropod and predator co-evolution

• However, in the fossil record it is difficult to infer types of relationships
  • We can infer some predator-prey relations like fossil mussel shells that show evidence of predation and whether it was successful or not
  • WE can see a correlation between mobile gastropods vssessile throughout geological time
  • Also seeing thickened shells and narrow aperture species increase throughout time

Law of constant extinction

• Probability of extinction is constant throughout the course of evolution
• A species could dissapear at any time
• All taxa must continue to evolve to avoid extinction - species that have been around longer are not necessarily better at avoiding extinction
• Every adaptation results in a Trade-off, and species constantly need to be adapting
• This supports the Red Queen Hypothesis

Biotic vs Abiotic interactions

• Co-evolution is exclusively with biotic interactions

Host-parasite co-evolution in honeybees

Coevolution-in-realtime_varroa-honeybees_2021.pdf

• Mite-resistant bee populations will open sealed cells containing larvae, look for mites, and eat the infected larvae or re-seal
• Some bees have different development times, for example if they spend less time as a mite then there is less time for the mites to become infected
• Untreated bees - have not received mite treatment, so they have co-evolved with the mite
• Treatment

Hypothesis

• Expecting reduced virulece in the parasite which should be influenced by the rates of reproduction in the mother mites (mite fecundity)
• They would expect that this would also result in higher Fertility rate
• Create a full-crossed experiment:

Results

Bees might have a mechanism to suppress mite reproduction, but these behaviours don't seem to be able to explain the result - the bees did not show enough recapping mechanisms

• Treated mites didn't find any shift in their ability to survive onselected bees
  • This indicates thatthere mightnot be a lot of movement between bee colonies

Follow up questions

• Compare fitness cost of VSH behaviour in infected vs non infected colonies
  • Do the VSH bees show this behaviour if they aren't infected with mites?
  • Do they have a statistical difference in reproductive output compared to non-VSH bees?
  • Don't infect any of them with mites
• Determine if the VSH bees success rate in identifying infected larva - do they make mistakes?
• Explore the effect of drone pupa interfereing with mite oogenesis
  • For example, we could remove all the drones before they pupate and see if there is an effect on mite oogenesis
• Environmental effects and VSH - reducing amount of nectar
  • Add another two colonies to the experiment with reduced nectar. Does the AWD colony preform better or worse than the treated colony when resources are limited?
• How many generations with no mites until the behaviour dissapears?
  • For example, test each generation and see if they start to show this behaviour, how long until they stop displaying this?