Exam 4 Flashcards
phylogenetic trees can be based on:
morphological traits, DNA, protein sequences
Occam’s Razor
the simplest solution is probably the best one (parsimony)
monophyletic group
group in which all species share the same common ancestor and all of the descendants of that ancestor are in the group
paraphyletic group
group in which all species share the same common ancestor but do not include all species descended from that common ancestor
why use phylogenies?
management (fungicides, rotate crop species, bury plant debris), treatment of disease, forensics, species recognition and biodiversity
asexual reproduction: mitotic
simple life cycles where policy stays the same (possibly with asexual reproductive structures), eukaryotic organisms only go through mitosis and no meiosis or fertilization
sexual reproduction: meiotic
complex life cycles with haploid (N) and diploid (2N) stages and specialized reproductive cells, gametic and sporic life cycles
sexual reproduction: sporic life cycle
all land plants and some algae, meiosis and fertilization, mitosis in both the haploid and diploid stages (N and 2N)
sexual reproduction: gametic life cycle
most animals and some algae, meiosis and fertilization, no mitosis in the haploid stage, all cells except gametes are diploid (mostly 2N), mitosis: 2N
parts of a flower
ather (stamen) - male parts
perianth - attracts pollinators
stigma (pistil) - female parts
hermaphroditic
flowers with both stamens and pistils
not hermaphrodites
some flowers have either stamens of pistils
both on one plant: monoecious
on separate plants: dioecious
costs of self pollination
inbreeding depression, reduction in fitness due to expression of rare, deleterious recessive alleles in homozygotes
benefits of self pollination
reproductive assurance
mechanisms to avoid inbreeding
self incompatibility (pollen can be blocked at the stigma surface and during growth to ovule), timing of pollen shedding or stigma receptivity, flower shape, dioecy
wind pollination
how most plants are pollinated, a lot of energy to produce enough pollen for wind pollination
animal pollination
most flowering plants are animal pollinated, attract multiple pollinators, and are generalists
pollinators are typically seeking a reward
nectar (sugar/amino acids), oils (provide fat), pollen (high protein)
pollinators are attracted by:
scent (sweet odor, pheromone mimics, dung/rotting meat odor) and floral pigments
pollination syndrome
floral traits associated with particular pollinators, can sometimes be used to predict pollinator from plant
bees
blue, yellow, or white flowers, good color vision and sense of smell, open during daytime, nectar: small volumes and concentrated
nectar feeding flies
light colored, open flowers
carrion flowers
prefers flowers that look and smell like rotting fish
butterflies
blue, purple, deep pink, orange red flowers, good color vision and sense of smell, nectar: often in narrow deep tubes
bats
light or dingy colored flowers, color blind, good sense of smell, active at night, open at night, plentiful nectar and pollen
moths
dull or white flowers, good sense of smell, active at night, less nectar in deep tubes
disperse seeds to:
reduce competition and inbreeding
seed dispersal mechanisms
water dispersed, wind dispersed, animal dispersed, seed hoarding, stick to fur
seed dispersal cues
color change and odor
convergent evolution
adaptation to similar environments can cause unrelated species to evolve similar traits
coevolution between animals and plants
adaptation to similar pollinators or plants can cause unrelated species to evolve similar traits
plants and non-animals coevolve
hosts and parasites can coevolve
ecology
the study of the distribution and abundance of organisms and the interactions that determine distribution and abundance
ecologists try to:
predict what will happen to an organism, population, community, or ecosystem and control the situation, minimize the effect of locust plagues by predicting when they are about to occur and taking appropriate action, predict which conservation policies are most likely to prevent species extinction and preserve biodiversity
scales in ecology
population, community, ecosystem, biome
carrying capacity
max number of organisms that an environment can support, population growth flattens when resources become limiting
possible fates of growing populations
exhaust resources: population crashes, nutrients added: carrying capacity fluctuates, richer medium: carrying capacity increases
