Week 6 Flashcards

Question

What is the egg discrimination like in bird popualions without brood parasites?

Answer 1

In Iceland there are no cuckoos so pipits and wagtails have poor egg discrimination potentially as a result of not having brood parasites

Answer 2

Imagine that there is no co-evolution with other species Evolution and adaptation only responded to the physical environmental pressures If the environment remains constant you would expect species to adapt and evolve until they fitted their niche perfectly They have all the adaptations needed to persist If a new species arises via speciation maybe its not so well adapted to its environment and may become extinct If this is true then the longer your species has existed for then the less likely it is that it will become extinct There should be some genera in the fossil record that have lasted a very long time (hundreds of millions of years)

Answer 3

If Van Valens hypothesis were true you would expect to see that some genera have adaptations that are so good that they persist indefinitely

Answer 4

Lots of genera have survives a small amount of time a few general have survived a long time

Answer 5

If you have a selection of genera, some of which have been around for a long time and some of which have recently evolved, and if there is no difference in their probability of extinction you get a linear distribution

Answer 6

However you may expect genera that have been about longer to have a lower probability of extinction If this was the case we would see a curved line

Answer 7

He studied sea Urchins, sand pennies, ammonites and sponges There was a declining linear relationship with a most species persisting a short amount of time and few species existing a long amount of time

Answer 8

So what must be happening is that the environment is changing So new adaptations are required - you can never be perfectly adapted to your environment

Answer 9

“Here, you see, it takes all the running you can do, to keep in the same place” Lewis Carrol

Answer 10

Running = evolving to a constantly changing environment Most obvious change to your environment is other species for e.g. parasites and predators Parasites and predators evolve to overcome host adaptations so everything is constantly evolving but they don’t become more fit

Answer 11

Predator and prey in fluctuating population ie high predators = low prey = low predators = high prey = high predators constantly in a cycle If the prey escapes the predator the population will increase until another predator replaces the old and the cycle restarts

Answer 12

Predator and prey in fluctuating population ie high predators = low prey = low predators = high prey = high predators constantly in a cycle Abiotic event happens which causes the predator population to rapidly to decline Prey species escapes and increases in size New predator species evolves which is a descendant to previous predator species

Answer 13

Molluscs are abundant as fossils and show a range of protective adaptations eg Thicker shells, Burrowing species. Cemented species and/or Shell repairs So we can infer some behaviours from the shells thickness Thick shells are more costly to make but better protection to predators Geerat Vermeij looked at the change in prey properties through time and the types of predator present Repeated constant evolution of new traits

Answer 14

Molluscivores evolved more complex ways to eat molluscs eg from whole body ingestors to specialised shell breakers and shell drillers Molluscs evolved a more increasing prevalence of protective mechanisms

Answer 15

Ants tend caterpillars of Lycinid butterflies The caterpillar has glands that feeds the ants sugar water and amino acids These are available because Lycinid caterpillars tend to eat leguminous plants so have high nitrogen in leaves, so its less costly to feed the ants If you remove the ants, other insects will lay eggs inside the caterpillar e.g. Tachinid fly Its costly to the caterpillar to give up sugars but its better than death

Answer 16

1 - Ant and caterpillar randomly meet and adapt, a drop of sugar water is released and the and coevolves a response in the ant to tend it 2 - Ant and caterpillar each evolve some traits – maybe the ant evolve tending behaviour because other insects like aphids also release sugar water – independent evolution of the behaviour which is applied to the relationship which then fit together

Answer 17

Phylogenetics

Answer 18

Some beetles still eat connifers but some moved onto angiosperms and there are many more of these species. If a lineage speciates a lot that is used as a proxy of ecologically success Many individuals who feed on angiosperms dispersing so diversification and speciating So why are there so many species of beetle? Probably because there are so many species of plant

Answer 19

Ants evolved from wasps and have been very successful

Answer 20

To help answer this a project was started to build a phylogeny for the ants One species of every genus was collected – some genes were sequenced – and a phylogeny was built

Answer 21

Length of the branches gives an indication of time Splits can be dated so we can see when most of the diversification happened Speciation is thought to be a proxy for ecological success – so splits are thought to relate to ecological success

Answer 22

In the Cretaceous – flowering plants started to diversify Two possible explanations 1 - Ants feed on plant resources 2 - Parasites of plants are potential prey for ants

Answer 23

Potential loss of function mutation Or selection against fur --> no hair mean fewer parasites

Answer 24

Mutalism Predation/parasitism Altruism Competition

Answer 25

Exchanges take place between an actor and recipient and can have positive and negative effects on both.

Answer 26

In predator/parasitic relationships the actor gains fitness and the recipient looses fitness from the actors behaviour

Answer 27

The actor gains fitness and the recipient gains fitness from the actors behaviour

Answer 28

This is a behaviour that increases another individuals fitness at a cost to ones own fitness On its own altruism should not evolve because altruistic individuals appear to have lower fitness

Answer 29

Alarm calls -> meerkats Nest helpers -> Scrub jays Social insects

Answer 30

Kin selection – natural selection can favour altruistic behaivour between kin e.g. Florida scrub jay Reciprocity – can be direct or indirect – “you scratch my back, I’ll scratch yours” eg allogrooming - baboons scratch each others backs. This requires memory and individual recognition help those who help me

Answer 31

Two different species both incur cost to benefit the other Often with animal/plant on one side and a microorganism on the other (bacteria, virus, fung

Answer 32

Bobtail squid Squid provides food and housing (at a cost) to Vibrio fischeri bacteria Bacteria glow (at a cost) The glow lest the squid counter-illuminate the moon shadow, to avoid predation

Answer 33

Upside down jellyfish Jellyfish provides housing to algae Algae give up some of their photosynthetic product to the jellyfish

Answer 34

Cheating Imagine you have two kinds of individual on one side of a mutualism (helpers and cheaters) The helper will have a lower fitness to the cheater Kin selection and reciprocity cannot solve this problem

Answer 35

When Vibrio fischeri bacteria are grown in culture, non-glowing individuals arise by mutation and have a higher growth rate (fitness). The non-glowers are probably also arising inside the squid and should thus take over the colony, resulting in non-glowing squid

Answer 36

Mutualisms are the most omnipresent of any organism to organism interaction

Answer 37

Trophic mutualism Defensive mutualism Dispersal mutualism

Answer 38

Partners specialised in obtaining energy and nutrients E.g. Rhizobium and plant roots that form nitrogen fixing root nodules in exchange for sugars Cellulose digesting bacteria in the rumens of cows

Answer 39

Involve species that receive food or shelter from their partner in return for a defensive function Ants and ant plants -> ants defend plant but gain a stable home

Answer 40

Involve animals that transport either: Pollen in return for nectar Seed in return for a fruit reward

Answer 41

Ants cut leaved and feed to specialised fungus Fungus digests plants and makes ant food, feed their larvae Essentially the ants are fungus farmers

Answer 42

Different ant colonies keep different fungi Fungal colonies can be huge – e.g. big lecture theatre underground Others are small under a leaf

Answer 43

Fungus is vertically transmitted through ant colonies When new ant queens are born and leave to start their own colony they will take some of the fungus with them from their original nest

Answer 44

If you mix samples from two different genotypes of fungi gardens they will kill each other – emit chemicals

Answer 45

This creates an opportunity for parasites: Escovopsis mold

Answer 46

Ants host bacteria which produce antibiotics and protect the ant and the fungus

Answer 47

Red queen type thing - Predators are no better at killing their prey species after many generations of natural selection Co-evolution of Pseudonocardia and Escovopsis Pseudonocardia (bacteria): constantly evolving more effective and selective compounds to kill Escovopsis Escovopsis (mould): constantly evolving resistance to antibiotics

Answer 48

If you wash the ants, many bacterial species can be isolated These bacteria also kill Escovopsis

Answer 49

Each ant has as many as 10 different bacteria - microbiome

Answer 50

So the ants are producing many anti Escovopsis drugs which are changing all the time This maintains effectiveness as the Escovopsis can not have total resistance to that many antibiotics This is similar to how tumours and antibiotic resistant pathogens are targeted and treated now

Answer 51

Vertical transmission - One coevolved species: Pseudonocardia evolving in arms-race fashion against Escovopsis Horizontal transmission - Ant “recruits” many useful species of bacteria from the soil. No need for an arms race

Answer 52

Phylogenetics If specific Pseudonocardia species had coevolved with leaf cutter ant species -> then we might expect to see more similar ant species with more similar Pseudonocardia ISome instances where Pseudonocardia had been picked up and then it would stay with those species – co-speciation This would cluster on a phylogenetic tree

Answer 53

Mueller collected sequences for Pseudonocardia from a database and built a phylogeny Many isolated from the soil Those from ants are highlighted in yellow These are not clustered, Pseudonocardia evolved many times to colonise ants

Answer 54

Mueller et al. concluded that Pseudonocardia have regularly been recruited from environments sources (soil) eg Horizontal transmission However this is not a very strong test… It was based on limited data

Answer 55

Colours link the ants/pseudocardia to the fungi - grouping on the tree Cafaro et al. concluded that some Pseudonocardia species have been recruited from the soil and passed down the generations and co-diversified and co-evolved with the attine ants

Answer 56

Barke et al. used a combination of genome scanning and tandem multispectral spectroscopy to show that Pseudonocardia produces an (antifungal) nystatin compound that is new to science. Suggests that Pseudonocardia has evolved a new compound Consistent with innovation and vertical transmission/coevolution, arms-race hypothesis

Answer 57

Vertical transmission - One vertically transmitted symbiont: Pseudonocardia, evolving in arms-race fashion against Escovopsis Horizontal transmission - Many screened-in useful species from soil

Answer 58

The attine ants can selectively recruit anti-biotic bacteria from the soil (but they need some help priming the pump)

Answer 59

Corals keep antibiotic producing bacteria in their surface mucus After bleaching disease causing bacteria dominates

Answer 60

This bistability can be modelled using 4 ‘simple’ equations

Answer 61

dS / dt = change in substrate (food) dB / dt = change in beneficial bacteria (antibiotics) dA / dt = change in antibiotics dP / dt = change in pathogenic bacteria (no antibiotics)

Answer 62

Scramble = faster growth = winner Interference = better fighter = winner

Answer 63

Antibiotic production is interference competition

Answer 64

We have alternative stable states ‘bistability’ Who wins depends on starting conditions

Answer 65

If you start with more Pathogens, then the Pathogens win.

Answer 66

If you start with more Beneficials AND there is lots of food, then the Beneficials win.

Answer 67

Antibiotic production requires lots of food which is used to kill pathogenic bacteria

Answer 68

Vertical transmission ‘primes the pump’

Answer 69

Pseudonocardia allows selective recruitment of another Actinobacteria Because antibiotic-producing bacteria are resistant to antibiotics (the ‘resistome’)

Answer 70

Vertical transmission – Initial Pseudonocardia Horizontal transmission – other actinomycetes

Answer 71

Worsley et al., used stable isotope labelled sugar water and showed that the ants do feed lots of different kinds of bacteria, including Pseudonocardia and Streptomyces

Answer 72

Holmes et al., competed Streptomyces against a series of non-antibiotic producing bacteria Streptomyces won only when the agar was filled with Pseudonocardia toxins.