Envirothon Wildlife K1: Wildlife Biology

Synapomorphies

shared, derived trait found in two or more taxa that originated in their most recent common ancestor

amniotic egg

• claws/nails at the end of digits —> digging, burying of eggs

• egg-tooth on snout —> facilitate hatching

• complete loss of water-breathing larva

• complete loss of lateral line system

• internal fertilization through penis

two sacral vertebrae

formation of the astragalus (foot bone - tarsal - that articulates with the tibia - shin bone

Lissamphibia (amphibian) egg

small and simple

embryo develops inside perivitelline space (fluid-filled gap between the zona pellucida - the outer protective shell - and the cell membrane of an oocyte) inside vitelline capsule (fibrous extracellular coat) inside a thick jelly capsule

limited gas exchange (through simple diffusion)

low metabolic rates in embryos —> risk of asphyxiate (death by suffocation) —> eggs must hatch at early developmental stage

Amniotic egg features

• air-breathing egg

• semipermeable leathery/calcareous shell

• albumen (+ other proteins)

• 3 extraembryonic membranes - work together to manage gas/water/nutrient exchange b/w embryo/yolk/albumen/exterior

  • chorion: encloses embryo + yolk + other membranes; facilitates gas exchange with exterior

  • amnion: encloses embryo

  • allantois: receive nitrogenous waste products from embryo (CO₂); facilitates gas exchange; develops into urinary bladder

  • yolk sack: encloses yolk mass (large compared to anamniotes —> doesn’t divide as zygote cleaves); facilitates transfer of water + nutrients to embryo

• arrangement modified —> placental mammals: yolk + shell suppressed, membranes modified into placenta + umbilical cord; birds/crocodylians —> shell membrane heavilty calcified into rigid shell

Amniotic egg advantages (perchance)

• allow embryos to develop quicker and to greater extent before hatching

• allow animals to not depend on water bodies in reproduction/larval stages

  • reduce competition for pools of water for maturing larvae

  • avoid predation by aquatic predators

Amniotic egg drawbacks (perchance)

• require specific environments

• heavy demands on parents

• egg can be laid and forgotten

Amniotic egg precursor

• relatively large egg with:

  • some kind of membrane to hold together

  • require internal fertilization

  • require embryos to use a gas-exchange structure (ex. gills of caecilian embryos)

• laid by relatively small animal able to find moist microclimates

Home range

area traversed by an individual in its normal activites of food gathering, mating, and caring for young; area an animal regularly uses to feed, rest, and carry out daily activities

established to manage resources and reduce conflict (avoid crowding)

movement within range may be irregular (based on water/food availability)

bordered by unsuitable habitats

animals stay in home range as long as food, water, and shelter requirements are met

Core area

region within home range where an individual spends 50% of its time (bedding, preferred feeding areas)

Territory

a type of home range; established when an animal/group actively defends an area and its resources for it-/themselves

often occurs when resources are abundant + reliable —> area under constant use by animal (may not maintain territory if resources diminish (cost > benefit), or are plentiful enough (defense is unnecessary))

specialized territories:

• antelopes set up during rutting season —> spend little time eating/drinking —> “territory just for the ladies” 🤧

  • rhinos allow neighboring bulls to enter for water as long as they move out afterwards and show submission to the territorial male and don’t “try anything with the ladies” (ig bro)

Signaling ownership of territory

communication:

• scent marking (urine, dung, scent glands)

• rhinos and civets use middens to warn intruders (communal dung pile to inform about resident’s health, group size, strength)

• vocalizations (lion roars, female leopard’s rasping call) —> signals health, dominance, readiness to defend territory, inform potential mate of presence

defending:

• visual display or vocal warnings before fighting

• usually animals try to avoid direct combat

White-tailed deer seasonal movement

generally not territorial

• in spring/when doe is about to give birth, she drives off other deer from birthing territory (temporary - 1-2 days)

• in fall, buck partied up with a “hot doe” drives off potential rivals —> territory around ground doe is happening to be standing on

• yearling bucks (young bucks, 1.5 yo) tend to be more aggressive —> causes them to disperse; older bucks less likely to change established home ranges (just avoid each other/use different areas of overlapped ranges)

home ranges can range from < 1 sqmi (rich agricultural land, densely developed areas) to ~15 sqmi (poor quality habitat, low deer density, dispersed resources)

movement variables:

• habitat (food, cover, water) - principal factor of how much/how far/where deer moves within home range —> better quantity/quality of variables = less movement needed

• hunting pressure —> bucks move less during daylight/move in thicker cover

• mating - causes bucks to move:

  • nomadic deer that travel far over several days, especially if does are few and dispersed

  • some make periodic excursions outside home ranges and return within 12-24 hr, many times to 2+ focal points within home range that they revisit every 2 days (likely to see female receptiveness)

  • some are home bodies and remain within their home range, especially in core areas (may have one or many cores) —> could happen because many does or personality

• seasonal shifts —> dietary availability/preference change

  • proteins in summer —> carbohydrates and fatty food in fall

  • move based on different ripening timings

• climate/season - migrate based on seasons (ex. to wintering areas); can be as far as 10-20 miles away —> both summer and winter core areas considered part of home range

  • milder climates: deer might move to dense bottomland softwood cover and/or south facing slopes in winter

Tracking beavers

American beaver: once prized for pelt; now often considered nuisance for damage they cause (estimates ~millions of dollars in southern states)

MSU investigate beaver ecology to improve management practices of populations for positive effects as keystone species or negative effects as agricultural/infrastructure pests

Isidro Barela (master’s student in NM) researching how to predict areas where beavers may live so land managers can identify and manage for damage that may arise

• Maxent: uses known beaver locations to predict habitat suitability

• Expert Opinion Models: predicts habitat suitability using environmental variables evaluated by beaver experts to make predictions —> better performance

discovered organisms (up to 2025)

~2.2 million animal/plant species categorized worldwide

~1 million insects

~370,000 flowering plants

~230,000 other invertebrates

~6800 types of mammals

camouflage

(a.k.a. cryptic coloration) a defense mechanism/tactic used to disguise appearance, usually to blend with surroundings, mask location, identity, and movement allows prey to avoid predators and predators to sneak up on prey

factors:

• physical characteristics: fur vs. feathers/scales —> fur is generally by season (summer vs. winter coat); feathers/scales can be changed more regularly

• species behavior: living in groups vs. alone —> zebra stripes make them stand out but by living together (herds), it is hard to differentiate individuals —> hard to stalk individual animal

• predator behavior: color blind predator —> prey doesn’t need to match color to surroundings (lions color blind —> zebras can be black and white)

Mimicry

one organism looks or acts like an object or another organism

• background matching: most common; conceal by resembling surroundings in coloration/form/movement

  • deer/squirrel have “earth tones”; flounder match speckled seafloor habitat; walking stick/walking leaf insects —> looks and moves like sticks/leaves (swaying)

• disruptive coloration: identity/location disguised through coloration pattern —> predators misidentify what they are looking at

  • many butterflies have large circular patterns (eyespots) —> look like eyes of larger animals (owls perchance) —> confuse & misdirect predators

aposematism

warning coloration; highlights identity, makes predators aware of toxic/dangerous characteristics

• larva + adult of monarch butterfly: yellow/black/white; orange/black/white —> eat milkweed —> poisonous to many birds (vomit causing)

• coral snake: brightly colored rings alert toxic venom

  • well known in animal kingdom —> other non-threatening species mimic coloration (batesian mimicry; harmless scarlet king snake)

countershading

top of animal’s body is darker in color, underside lighter; distorts shadows/illuminations to make it harder to see its true shape

• sharks —> blend in with darker ocean water below (protect against fishermen) / lighter surface water (help hunt prey)

creating camouflage

pigments, physical structures

biochromes: natural, microscopic pigments —> absorb certain wavelengths of light, reflect others —> appear to change colors

• octopus changes color/pattern/opacity of skin

prism-like physical structures: microscopic structures that act like prisms —> reflect/scatter light to produce color different from skin

• polar bear has black skin —> translucent fur reflects sun + snow —> appears white

change w/ environment:

• arctic fox changes coat seasonally

• octopus camouflage when there is a threat

• other species (nudibranchs - ocean slugs) can change through diet

chameleons change color to communicate/warn other chameleons

use of natural materials: don’t rely on coloration but attach/attract material to bodies to hide

• desert spiders attach sand to upper part of bodies to blend w/ sandy ground

olfactory camouflage: hide by covering up their smell/masking with another species’ smell

• california ground squirrel chews up and spits out rattlesnake skin, applies paste to tail —> smells like its main predator —> confuses rattlesnake (senses w/ smell & body heat)

animal density

number of animals in a unit area

• relies on counting

• using mathematical properties of “stationary” home range combined with wildlife video recording (unmanned aerial vehicles - UAVs - or underwater video recording devices), a robust estimate of population density can be made (averaged counts across independent frames divided by area surveyed by each camera)