Final Flashcards
Prey can thwart the efforts of predators in 3 ways
maximizing search time, maximizing handling time, diluting nutrient effectiveness / toxic and noxious compounds
Prey maximizes search time by
hiding, crypsis, mimicry
Prey maximizes handling time by
defensive weaponry, armour, shapes
Prey signal that they are of low nutrient value / have toxic noxious compounds via
aposematic signalling
Grazers and Browsers (searchers)
mobile, feed on nutrient-poor foods, often possess specializations of the mouth to most efficiently feed on low quality foods, ecologically important
Coevolution between plants and insects: advantages and disadvantages
biological arms race
advantages: little competition for food source, incorporate defence mechanisms of prey into own defence system
disadvantages: threatened if food source compromised
3 ways to gain nutrient material from indigestible polymers like cellulose and lignin
symbiosis adaptations, mechanism disruption through morphological adaptation, use of specific enzyme activities
Pogonophoran worms display symbiosis adaptations
specialized symbiosis with chemosynthetic bacteria that thrive near thermal vents (high sulfur, no light) – do not possess gut or feeding structures, bacteria only source of nutrients
symbionts undergo photosynthetic activity
production of sugars (maltose and glycerol) that are energetically rich, production of oxygen (very reactive, and additional production of hydrogen peroxides which are also very reactive – both lead to the formation of free radicals)
stress and symbionts
symbionts under stress release these reactive compounds at a higher frequency and may be of detriment to the host (eg. result in coral bleaching)
specialized adaptation in the grazer/browser
overcome challenges of the prey item, and may allow the grazer/browser to use the challenge of the prey item to its own benefit
grazer browser incorporation in nudibranchs
nudibranchs incorporate prey (cnidarian) nematocysts into epidermal structure (cerata – part of digestive system)
grazer browser specialization in sea urchin
Aristotle’s lantern highly efficient jaw-like structure to bite through kelp
grazer browser symbiosis in termites
endosymbiosis between protist (Trichonympha) and bacteria (in protist) to break down cellulose in gut
terpenoids
hormone-like compounds produced by plant species like cedar and pine tress
insects and terpenoids
insects have evolved to detect terpenoids using receptors, incorporate into metamorphosis and moulting processes as powerful signalling molecules
sawfly larvae
release gas when heads lifts which contains a volatile compound incorporated from plant food source
monarch butterfly
overcome mechanical defence (latex glycosides – difficult to digest, tase aversion), overcome chemical defence (toxic alkaloids) of milkweed plants to make themselves unpalatable
predator insects like the monarch, tardigrade, cicada, and aphid possess
specialized feeding structure (stylets) to pierce the phloem (transport sugar) of plant food source directly
cicada and phloem
used for cooling, stylet specialized structure not just for nutrient material
High CO2 compromises
compromises calcification by reducing availability of carbonate ions and by dissolving existing calcium carbonate structures – energy is required to combat this problem
High CO2 disturbs
disturbs acid-base balance by increasing CO2 in body fluids and tissues – energy is required to combat this problem
minimize capture by hunters
by increasing predator foraging and/or capturing time
groups and minimizing capture by hunters
better capacity to ward off predators with the release of toxins, faster detection and response to predators, confuse predators
invertebrate feeding behavioural consideration summarized in
Optimal Foraging Theory
Optimal Foraging Theory is strongly influenced by
trade-offs in decision-making economics, but rationality ≠ fitness
Optimal Foraging Theory
maximize energy input to increase fitness
profitability (P) = energy intake (E) / time (T)
Profitability in Optimal Foraging Theory based on factors like
travel time, handling time, nutritional value, capacity, access
Optimal Foraging Theory and prey size
crabs: small mussels are less profitable, large mussels are more profitable but harder to open
in suboptimal conditions, crabs will feed on sub-optimal mussels under food-restricted conditions
Optimal Foraging Theory and travel time between prey
P1 • travel time, variable
P2 • foraging time, variable
shallower slope indicates longer travel time and/or handling time
saturation point • stop eating – impacted by efficiency of food handling, nutrition, etc.
Optimal Foraging Theory model assumes
assumes need to feed, but how motivated are they to feed?
parasites
special type of hunter, usually much smaller than host, develop inside or outside host (some life stages more closely associated than others)
microparasites
multiple within host, immune system of host regulates parasitic load eg. malaria, Giardia
macroparasites
multiple outside of host eg. ticks. flatworms, roundworms
endoparasites
live inside cells, ecologically specialized in reproduction (synced with host), resource exploitation (tap into mitochondria), usually not very mobile (rely on cell cycle to transmit themselves), high reproductive output (highly dispersed)
evolutionary arms race between host genotype and parasite genotype
evolution of resistance to parasite – immune system combats parasites, involves strong fitness consequences
evolution to overcome resistance of host – strong selection of rare alleles in parasite following host immune response
host immune response carries memories of antigens so
parasites must chance their surface properties – arms race on the level of the immune system
host survival reduced
directly dependent on parasite load
host sublethal effects
in which case host genes are propagated in the next generation to continue to fight parasitic infection – life history traits shaped by parasites: affects age at maturity, fecundity, population growth rate – because energy is invested in immune response
host serves as parasite ecosystem
density-dependent intra-species and inter-species parasite competition of resources often resulting in resource exploitation through specialization, immune response of host exerts bottom-up control
In order to understand flight you need to understand how flight
impacts the medium around them
forces involved in flight
weight, drag, lift (perpendicular to drag but not necessarily perpendicular to movement), thrust (produced by flight)
wings beat using
a spinning movement (more helicopter than flapping)
wings create
vortices which create a lift force on the leading edge of the wind
Reynold’s number depends less on ____ and more on how quickly ________
Reynold’s number depends less on speed and more on how quickly wings beat
Reynold’s number, size, flight.
Proportionately more energy is required the smaller an insect is to produce life and combat drag
direct flight muscles
paleoptera (dragonflies and mayflies), many extinct species • cannot fold wing over abdomen, muscle attachment directly to wings, synchronous contraction to AP
indirect flight muscles
all other living insect groups (derived feature) • can fold wings over abdomen, muscle attachment indirect to wings, muscles attached at thorax, asynchronous contraction to AP (consequence of indirect flight muscles (co-occurrence) perhaps as insects got smaller (given smaller Re)).
using a variety of markers for musculature to determine specific role in flight, fruit fly has how many pairs of steering muscles?
13 pairs of steering muscles
locusts fly long distances by using
low thrust and little lift (low energy) to maximize efficiency
halteres
mechanoreceptors to increase stability that oscillate during flight, modified hind wings
de-activate halteres to resort back to 4 wings
de-activate ultrabithorax (Hox gene) to resort back to 4 wings
hawkmoth
able to hover really well, possesses large antennae instead of halteres, removal study: unable to hover, once re-attached the nerves partially regenerate and some stability restored
not all legs are used equally, so how many legs do you really need?
3 - Tripod model - to optimize stability, keep one limb on the ground at all times.
walking – 2 traits decrease with speed
percent support phase per stride, percent stability
trade-off in walking between?
stability and speed – what trait is more important in the given habitat?
legged locomotion has evolved how many time in arthropods?
3 times – crustaceans, chelicerates, hexapods
ballistic phase
airborne for a brief period of time eg. cockroach
undulatory gate
use body musculature to increase speed by undulating eg. myriapod – solves constraint between speed and stability
locomotion with tube feet
sea stars and echinoderms • use hydrostatic pressure and longitudinal musculature
increased size of sea star doe not correspond to increased speed because
selection acts strongly on the tube feet themselves – cannot be faster by adding more tube feet, need to modify tube feet themselves
behavioural mechanism independent of biomechanics
octopus swimming vs walking vs on land
crawling locomotion
hydrostatic pressure changes, pumping of hemolymph pro-legs “inflatable” eg. leeches and caterpillars
super-contraction in invertebrates
perforated Z-line
70-80% overlap in myofilaments in invertebrates
50% overlap in myofilaments in vertebrates
insect muscles have more of what type of myofilament?
actin
power in insect muscle vs vertebrate
originally thought to be more power in insect muscle, but when scaled, not much difference
swimming • Re determines how much, Re is more relevant in water because
drag, because water is more viscous
4 forces in swimming
thrust, drag, lift/buoyancy, gravity
swimming in low Re
viscosity dominates • cilia and flagella, power and recovery strokes
in exception to ctenophores, cilia is used for feeding only in
larger organisms – based on Re number, ctenophores could use a different structure for locomotion but retain cilia – use combs or ctenes (bundles of coordinated cilia) to overcome physical constraints associated with using cilia at their larger size
swimming in high Re
inertia dominates • use momentum to limit energy expenditure
jet propulsion in molluscs like the squid
mantle contractions (via heavily innervated and muscular collar structure) expels water at a high velocity out of funnel – more efficient to have separate water in and water out structures – more efficient than flapping (fins for finer movements)
jet propulsion in young cephalopods (paralarvae)
in the planktonic stages use the same jet propulsion mechanisms but must pump water constantly because viscosity dominates in this life history stage, small and slow paralarvae, no metamorphosis, behavioural changes associated with life history stages
minimal mantle width is
inversely related to velocity
jet frequency is
directly related to velocity
jet propulsion in amphioxus (lancelets)
via propagating waves (wiggly) using differential muscle contractions – similar movement in fish and tetrapods so likely heavily contributed to the evolution of tetrapod movement
amphioxus (lancelets) cilia
ciliated cells reduced in ontogeny which is closely associated with changes in locomotory mode – adult, cilia only used for feeding and excretory mechanisms
larval and adult life stages movement in amphioxus (lancelet) produces distinct difference in fields exerted on the water
larva • ciliated mode, laminar flow, slow, energetically efficient
adult •undulating mode, less laminar, fast, greater energy expenditure (but greater capacity to take up energy)
jet propulsion in swimming sea cucumber
to stay suspended
sensing and responding requires 2 interdependent components
neurobiology (information processing), behaviour (response)
receptors are structurally comparable but differ in innervation
photoreceptors, mechanoreceptors, chemoreceptors
photoreceptors – many animals can detect UVA and UVB light
300-400 nm
photoreceptors – many insects can detect IR light
700-800 nm
wavelength is inversely related to
energy
wavelength is directly related to
penetrance
animals possess receptors of different capabilities at different depths in the water column because
water acts as a wavelength filter
eyes evolved how many time
50-100 times independently, relatively quickly (~100,000 years) meaning the basic requirement of the eye (opsin) already existed
basic requirement of the eye
opsins • conserved group of proteins that may have a single origin, evolved a much longer time ago and over a longer period of time than eyes, transmembrane proteins, possess chromophores
opsins possess chromophores
convert electromagnetic energy to chemical energy
3 types of eyes
simple eyes, more complex eyes, compound eyes
simple eyes
ocelli • pigment cups, no lens structure, unable to focus light, Daphnia nauplius
more complex eyes
pinhole eyes, camera eyes
pinhole eyes
no lens structure, unable to focus light, produces dark images and soft-edged images, parallel rays of light pass through pinhole and interact with retina, evidence in Nautilus and ammonites, further evidence of pinhole eye diversification so must be adaptive
camera eyes
lens structure, able to focus light, less waste of light: larger opening and ability to focus light so much higher sensitivity in lower light conditions, focal plane defined by lens shape: must modify lens shape to interpret/focus different depths
squid and octopus have camera eyes
high resolution (based on density of photoreceptors, >20 million), but lesser than human (100-200 million) – but clear convergence of eyes system in lineages separated by hundred of millions of years, octopus eye has an extremely developed optic ganglion
“compound eyes”
jumping spiders • possess ocelli (no lenses) so neurologically connect 2 pairs of eyes to establish depth of field – front pair detect prey in high focus, side pair direct eyes where to focus using broader view
sea urchin tube feet • possess opsins (no lenses) so neurologically connects pairs of eyes to establish depth? – opsins belong to a family of proteins not exclusive to light sensitivity, study found no shielding pigments like carotenoids so tube feet opsins must either interpret ‘raw’ light or have a different mechanism –spines act as a different mechanism: create a shading pattern as they actively move as if each tube foots acts as a unit in a compound eye
true compound eyes
resolution determined by the number of ommatidia, involves complex sensory processing in the brain, ability to view different directions at the same time
trade-off in true compound eyes, crayfish
focus vs visual field
true compound eyes in crayfish and stomatopods
crayfish: rhabdome: translucent cylinder forming part of light-sensitive receptor in the eye of an arthropod, composed of rhabdomeres, harder to resolve but broadens view and increases light sensitivity
stomatopods (mantis shrimp): 16 distinct eye pigments (huge range of wavelength sensitivity), colour filters (narrow wavelength to accommodate to appropriate pigments receptor, can see polarized light (increase in contrast for hunting), take advantage of broad light environment, useful for speed and precision in hunting
chromatophores
class of pigment cells that reflect and/or absorb light, including iridophores
iridophores
reflect light, cephalopods
in addition to iridophores, cephalopods also possess
crystals • cytoplasmic structure made of guanine at the surface of the skin that manipulate light
sense polarized light using
2 polarizers: photoreceptors arranged in specific way (orthogonally) at the intersection of the microvilli to remove stray light to increase contrast
use polarized light
to see hard structure on soft-bodied organisms, increased contrast
cephalopods use chromatophores to change colour
pigment granules in the pigment sac become more or less obvious based on muscle contraction and relaxation (50xSA), conscious coordination (active behaviour) to respond to environment, selection acts on behaviour because it is under neuronal control
cephalopods use chromatophores of 3 colours
yellow/red/brown which is limiting, but iridophores (in front of chromatophores) are structurally associated to change hue of pigments sacs
scallop eyes
mirror lenses, 2 sets of retina split different wavelengths of light into different parts of retina, does not focus light but interprets wavelengths of light
cubozoan (box jelly) eyes
live in the open ocean but are sometimes washed into mangroves so needs to avoid damage and predation:
1 pair of camera eyes, open ocean, recognize farther objects
2 pairs of ocelli eyes, detect mangroves
serve as an alternative to chemosensation which would be rather useless in the open ocean
chitin eyes
simply eyes with low resolution, detects light and dark, well protected individuals so just aware of diurnal cycles
eyes from cambrian
500 mya, evidence of crustacean rigid eye structures: first recorded stalked eyes, evidence of complex eyes and rigid lenses, diversification of forma and function in Cambrian explosion, huge advantage with evolution of eyes as supported by broad range of eyes
Trilobites fossilized calcite lenses similar to today’s complex eyes but shade formation to distinguish diurnal cycle
brittle star eyes
response to light is long known (change in colour), calcite lenses on dorsal surface, different form and function than cephalopods but similar results, response to light ≠ ability to distinguish
integrating sensory input: photoreceptors and photoreceptors
compound eye and compound eye: flies create optical flow patterns, can decouple eye input by providing 2 separate images to study information integration, one 4-5 cells are responsible for sensory input integration
integrating sensory input: chemoreceptor and chemoreceptor
smelling and tasting: small molecules that are diffuse in some medium are transported to the surface membrane
osphradium (olfactory, sea snails) potentially homologous to molluscs
nuchal organs (chemosensory), contained in ciliary pit , useful taxonomically, in first section of polychaetes, unknown mechanics
integrating sensory input: chemoreceptor and photoreceptor
olfaction and vision: fruit fly on pedestal appears to have difficulty orienting itself towards food source when one sensory system (vision) is taken away
integrating sensory input: mechanoreceptor and chemoreceptor
acoustic and tasting: spiny lobster antennae produce acoustics and are chemosensory
rhopalia
multi-sensory organ in the mantle region: light sensing eyes and statocyst (visual and mechanical information)
statocyst
contains the statolith (mineralized component) in bell region of scyphozoans and hydrozoans • planktonic adaptation to detect 3D environment
ctenophore aboral organ
contains statocyst, statolith held up by bundles of cilia, ciliated cells connect to ctene rows for fine motor control, use of diffuse nerve net, no CNS
assume ancestral structure of aboral organ in ctenophores
based on basal phylogenic position (very different from hydrozoans and scyphozoans) but perhaps this is a very specific adaptation to ctenophores? unknown
decapod statocyst
at basal article of antennules, replaced at molts because associated with integument
statocysts can be used to determine age in fishes and cubozoans
because of specific statolith growth rates
larvacean melanin droplets
melanin in lipophilic matrix moves differentially to body fluid, linked to nervous system via sensory cells to orient individual in 3D space, urochordate adaptation to planktonic life
2 special organs in spiders
trichobothria and lyriform organ (slit organ)
trichobothria
elongated seta structure one of the most mechanosensitive structures in animal kingdom, elongate so small movements stimulate sensory cells which are further amplified by the membrane
lyriform organ (slit organ)
detect endogenous strain (own movement) related to silk production (to assess torque and tension of silk) used in silk loading and web building/repair
cricket tympanum
acoustic mechanosensory structure used in intraspecies communication – parasitoid flies deposit eggs on crickets that produce specific wavelengths to ensure host specificity
halteres or antennae in moths
detect rotational forces in insect flight
calliphora eyes
possess both complex eyes (image-forming) and ocelli (light detection)
sensory integration calliphora
visual cues and mechanical cues integrated by the neck organ which stabilizes and directs the insect, 21 muscles connected to neck organ to coordinate head movement according to sensory input
mosquitoes
abdominal stretch receptors detect how much blood has been ingested based on expansion of abdomen, when to stop drinking, regulates growth in metamorphosis
only female mosquitoes feed
anterior to posterior cutting of nerves severs PNS to CNS connection leads to hyperphagia, longer feeding time, more eggs laid, the more anterior the cut – stretch receptors and less sensitive anteriorly because most abdominal expansion is observed in the posterior abdomen with feeding
hyperphagia
increased blood volume in body than normal, the 2nd abdominal segment is the critical threshold for hyperphagia, leads to indefinite drinking, possible death
survival is meaning less without _____, so
reproduction, so selection (and therefore fitness) is based on reproductive success
trade-offs can be measured by
the fitness of the progeny
the fitness of the progeny is directly linked to
female parent investment
current reproductive effort relates to
future reproductive effort, however relationship is not linear because factors shape life history trade-off relationships
expenditure per progeny relates to
fitness of individual progeny, however relationship is not linear because limits exits, high expenditure per progeny does not equate to more realized progeny fitness
asexual reproduction
efficient (no partner) but clonal offspring has ‘no’ variation compared to sexual offspring
sexual reproduction
less efficient (partner) and variation in offspring no always an advantage
facultative asexual reproduction
Daphnia, reproductive behaviour consequence of environment
obligate asexual reproduction
rotifers, reproductive behaviour consequence of environment
germ line
unique to animals but particularly important in sexually reproducing animals, segregated early in development from the cells that specialize into various tissue (meaningless to next generation), only change in germ line are relevant, only selection on germ line (not somatic line)
in asexual reproduction, there is selection on the ____ level
clonal level in the form of propagules, so the somatic cells are relevant to the next generation
alternation between reproductive strategies is historically reserved for plants but animals can cycle between
phases (not between generations)
obelia, medusa
obelia, asexual phase, bud from polyp
medusa, sexual phase, main dispersal stage
asexual fission
never described in molluscs or arthropods, but is described in echinoderms, annelids, sponges, nemerteans, hydra, polychaetes
animals that demonstrate asexual fission have
much greater regenerative capacities because it is a natural part of reproduction
physalia, both reproductive phases
exist within the same organism
hermaphroditic sexual reproduction is
separated temporally: sequentially, simultaneously
in the absence of a mate, mate with yourself
inbreeding, reduces genetic variation
crepidula are sequential hermaphrodites
males settle on females to ensure very direct fertilization, if female dies (large, more egg production) the largest male assumes female sex
displays or fourtship
dangerous but effective
loligo
only 1 reproductive event but massive amount of eggs
if you are not hermaphroditic, but are sessile
must time/settle near opposite sex so gametes have a bette chance to meet
corals are an extreme case of free spawners
reproduce once per year, very controlled (timed) event linked to lunar cycles etc, larvae are short-lived and settle
small mountains act like high elevation sites
because they are relatively high
mountains exhibit large climatic gradients over
short elevations
ant abundance and diversity greatest at
mid-elevation (tropical rain forest)
rove beetles abundance and diversity greatest at
high-elevation (tropical cloud forest)
temperature-stable environments, species are historicall
successful, but will suffer in the face of climate change because adapted to having no need to disperse (sedentary) / deal with climatic variability, and locked into tight elevation plans
Why have sexual reproduction?
environment instability, saturation, red queen hypothesis
environment instability
in rapidly changing environments, adaptation is faster with asexual reproduction but relatively un-flexible but bet hedging in sexual reproduction
bet hedging
organisms suffer decreased fitness in their typical conditions in exchange for increased fitness in stressful conditions
saturation
capacity of environment, competition, diversification through sexual reproduction (resource partitioning) compared to decreased likelihood to explore other niches with clonal reproduction, more room in environment is associated with asexual reproduction
red queen hypothesis
selection leads to changes in organisms to ‘stay where they are’ so co-evolution system (arms race) with close association between 2+ components, need sexual reproduction for flexibility because asexual reproduction is too slow in evolutionary change
Mutation Purging Hypothesis
polyandrous system • more male, more genetic exchange, mutation purging, protection from inbreeding
monogamous system • equal parts sexes, reduction in survival with inbreeding
process of settlement of marine invertebrate larvae involves multiple factors
recruitment, metamorphosis, change in life style
recuitment
addition of new individuals to a population (count juveniles in benthic habitat), migration is not true in the context of planktonic to benthic life phases – only through reproduction
causes for variation in recruitment
production (linked to survival of larvae), larval settlement, growth and variation of settled individuals
metamorphosis
transition between planktonic and benthic, links 2 life phases, primarily from sexual reproduction, exhibits huge divergence between 2 life forms
dispersal of larve
larvae = passive particles, but there is actually less dispersal in larvae than passive particles because of habitat selection
teleplanic larvae
delay settlement process and thus recruitment and can cross huge ranges (huge amount of time in plankton), response to cues
larval behaviour can allow for retention
low dispersal (known habitat), tides regulate migration (associated with settlement success)
Pokey is a transposable element that inserts itself into
Daphnia 28S rRNA genes
Pokey render the 28S RNA dysfunctional, but persist in populations because
its is extremely rare
semelparity
massive reproductive event followed by death
iteroparity
fewer young per reproductive event but many reproductive events
invertebrate trade-offs are very different from vertebrate trade-offs based on
the environment
more then 500 combination of life history strategies with huge diversification in relatively constrained lineages, bt
some strategies are more correlated than others because size determines possible fraction of the total adult body size dedicated to gametes
larger invertebrate marine forms
many/low quality • snails, brittle stars, urchins, cnidaria • broadcast spawners, external fertilization, planktotrophy, multiple reproductive events, gametes used for storage (easily shift between nutritional and reproductive investment)
smaller invertebrate marine forms
few/high quality • often live in interstitial environments • barnacles, krill, copepods • small or no body cavity, eggs not discharged, brooding, lecithotrophy, frequent reproduction (less seasonality, not as dependent on environment for nutritional support)
freshwater and terrestrial invertebrate forms
nematodes, insects, copepods, size and habitat • viviparity/cocoons/impermeable eggs, structurally complex gamete morphology, internal fertilization, low fecundity, yolky eggs, brooding, long term storage of donor sperm, hermaphroditism, diapause
diapause
form of suspended animation during development where growth and development essentially stop, for a somewhat unpredictable environment, stress response (but larval cloning is also a stress response), rare in marine benthic
freshwater and terrestrial life history traits are similarly tough
osmotic challenges from the environment: air desiccates, freshwater swells
maternal investment
planktotrophy • feeding structures, low maternal investment, long dispersal, high mortality
lecithotrophy • no feeding structures, high maternal investment, short dispersal, low mortality
sea star adults are indistinguishable
yet one is planktotrophic, one of lecithotrophic
Heliocidaris genus of echinoderms, sea urchin
tuberculata and erythrogramma
tuberculata
tiny egg, long-lived larvae, proteins in egg, feeding
erythrogramma
huge egg, short-lived larvae, lipids, non-feeding
evolution of alternative life histories over small divergent time frame
increase in egg size, loss of feeding, acceleration of development, loss of structures
hybrids
viable hybrids prove the evolution of alternative life history strategy evolution?
tuberculata sperm, erythrogramma egg, no in natural environment
