Diversity II Notes Week 10
Diversity II Notes Week 10 211
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This 11 page Class Notes was uploaded by Jacob Erle on Friday April 1, 2016. The Class Notes belongs to 211 at Syracuse University taught by Justine Weber in Spring 2016. Since its upload, it has received 35 views. For similar materials see Diversity of Life II in Foreign Language at Syracuse University.
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Date Created: 04/01/16
Diversity of Life II Notes Week 10 Social Insects Video Lectures – Dr. Scott Turner 1.) Introduction to the Social Insects Primarily found in Orders Hymenoptera (wasps, ants, bees) and Isoptera (termites) Characterized by: Living in social systems, consisting of sterile workers and royal pairs overlap of generations in workers, which have shorter lifespan than royals specialization of labor: foraging, brood care, sanitation, nest maintenance, and reproduction caste system different roles can have different morphologies; worker caste is more generalized, soldier ants can have large forceps, reproductive caste have wings Insect Colony acts as Superorganism Body Colony Cells individuals in Colony Organs Specialized Labor (with different castes) Reproduction done by royal pair (king and queen = gonads) Coordination, maintaining homeostasis in the body similar to nest maintenance Superorganism serves as evolutionary model, with differing grades of sociality Cooperative Reproductive Overlap Brood Care Castes between generations Solitary Quasisocia l Semisocial Eusocial Most social insects’ origins originated in Creatceous (Aculeate wasps), and during the Cenozoic Era they diverged into several lineages, and has developed at least 34times independently (see Geologic timeline) Termites social origins lie further back, during Triassic and possibly Permian period, and sociality evolved independently probably only once, and earlier than in the wasps (ancestorssocial cockroaches) Sex determination differs Hymenoptera – haplodiploidy Isoptera – sex chromosome diploidy (think XX and XY in humans) Sex ratios also differ Hymenoptera (holometabolous) – worker caste is all female Isoptera (hemimetabolous) – 50:50 both orders show similarities in social organization (caste system): reproductive, worker, soldier with specialization among role Very real example of CONVERGENT EVOLUTION 2.) Kin Selection and the Evolution of Sociality in Insects Evolution of altruism – sacrificing one’s own reproduction to benefit reproduction of another doesn’t agree with postulates of Natural Selection Altruism does exist in social insect colonies (reproductive pair vs. sterile workers) Origins of Sociality Fitness (Sewall and Wright) – transmission of genes across generations J.B.S. Haldane – proposed that it doesn’t matter who transmits genes if the genes are identical – principles of evolutionary fitness will remain constant Inclusive Fitness –fitness includes direct transmission of genes across the generations, and transmission of copies of the same gene by others Kin Selectionprobability of protecting related organisms will protect your own genes (parents and offspring) Degrees of Relatedness Path Lengths Coefficient of −L(p) Relationship r= ∑ 2 p Paths of Relationship In Hymenoptera: Relationship Relatedness Parentoffspring 2 =0.5 2 2 Brotherbrother 2 +2 = 0.5 Brotherstepbrother 2 =0.25 Cousins 2 x 2 =0.125 nd 6 6 2 Cousins 2 + 2 = 0.03 3 Cousins 2 x 2 = 0.008 sex ratio skewed more towards the female workers induce queen to produce sisters and daughters only 1 male mates with the queen, high level of fidelity seen Reproductive Breakouts – reproduction by other bees (daughters) than the queen can give rise to sister queen, which inevitably can give rise to new colonies workers can control new development through providing developing larvae with ‘royal jelly’ in turn controlled by queen with select pheromone secretions *Remember – bees are holometabolous In Isoptera: 50:50 sex ratio hemimetabolous metabolism – development stages in instars instar can become nymph, then reproductive adult instar can even regress a stage to become a nymph Reticulitermes flavipes can consist of one central colony (contains reproductives) and satellite colonies (sterile workers) control of reproduction relates to control of development tropholaxis – pheromones secreted by queen will induce development of sterile workers not as strongly seen in those satellite colonies further away from the main one 3.) The Superorganism Organismlike systems: Biological Coalition between organisms, social insect colonies and/or symbiotic organisms strong degree of genetic affinity between one another Reproduction by proxy germline individuals are the privileged ones Common physiological interest specialization differentiation division of labor cognitive awareness Coalition members may divert their own reproductive contribution to other members in order to give them more energy and greater fecundity Division of Labor In Hymenoptera: foragers collect nectar and pollen from the wild foragers deliver to worker bees inside the hive workers convert nectar to honey to be stored, pollen is stored activities of specialists are coordinated and regulated between members of the colony use behavioral feedback loops to keep coordination foraging dependent on nectar (constant) and pollen (decrease with increasing energy reserves) In Isoptera: in digestive tract their paunch contains special microorganisms used in wood digestion wood contains cellulose – good energy source but largely inaccessible to animals usually only accessible source for bacteria, fungi periodic molting must also come with reuptake of digestive microbes, which come from other colony members symbiotic interactions termites able to digest pretty much anything, digestive fungi get constant food source and protection from predators 3/31/16 Noninsect Invertebrates – Arthropods Traits bilateral symmetry segment body body divided into head and trunk welldeveloped exoskeleton, molted at intervals for growth; made of chitin (nitrogenous polysaccharide) open circulatory system complete gut Phylogeny insects derived from crustaceans and myriapods Subphylum Crustacean (70,000species, twice as many amphibians, reptiles, birds and mammals combined) Morphology fewer species than insects but more diverse in form head section has 5 pairs of appendages, 2 pairs of antennae biramous appendages – branch out into 2 Habitat primarily aquatic Class Brachiopoda (“gill foot”) much gas exchange done using gills found on long feet Morphology last segment of thoracic appendages used also for feeding and locomotion Habitat filter feeders, many freshwater species Life Cycle and Reproduction asexual is primary mode (only females are produced) when conditions are unfavorable males will be produced to make a ‘resting egg’ (escape pod) – can help with transportation or may sink to water body and won’t emerge until better conditions resume some are purely asexual Examples and Human Uses Daphnia (Water fleas) can be between 0.53mm long – crucial filter feeders for lake bodies Artemia (sea monkeys, brine shrimp) – inhabit salt lakes, estuaries; harvested in aquacultures Eubranchipus (fairy shrimp) – resident of vernal pools and fishless pools (helpful for amphibians that rely on these temp water bodies) may also be harvested, hatched and reared to feed fish (Group Cladocera) *Phenotypic plasticity in Daphnia – can change shape in response to presence of predators (development of sharp tooth) Polyphemus – predatory Leptodora Invasives – Cercopagis, Bythotrephes Class Ostracoda (‘shell’), 68k described species (many of them are from fossils) Carapace covers the animal (‘seed shrimps’) found in both freshwater and marine systems (in the water column or found on the very bottom) reproduction similar to those seen in Cladocera; sometimes will mate in swarms used as indicator species Class Copepoda ~8,50014,000species some freshwater, mainly marine (some are parasitic) Body plan st prominent 1 antennae Ecology most abundant herbivores on earth (phytoplankton consumers) Life Cycle and Reproduction obligate sexual; undergo metamorphosis (indirect development), some make resting eggs (can be very long lived, can be over 300years) nauplius larva Infraclass Cirripedia (‘hairy foot’) Over 1000 species Barnacles Body plan thoracic limbs modified to filter and have no abdomen Habitat all marine (some live in intertidal zone) attach to hard surfaces Ecology sessile, filter feeders Life Cycle hermaphrodites, many don’t selffertilize Ex. goose neck barnacles (consumed as delicacy in Japan, Spain) uses special cement to adhere to various substrates Class Malacostraca Contains 6075% of crustacean species amphipods (‘scuds’), shrimp, lobster, crab Body Plan head, thorax and abdomen Habitat marine, freshwater and terrestrial Ecology pelagic and benthic Ex.Mantis shrimp, common in tropics and subtropics *Don’t cross these guys, very powerful Ex. Euphausia superba – krill, dominant in Antarctic vital component for polar seas ecosystems Ex. Penaeus (pink shrimp) Ex. Crayfish – omnivorous, some show maternal care for eggs (carrying, even brooding offspring) Ex. tropical freshwater shrimp – useful in nutrient cycling in aquatic rivers Ex. banded shrimp Ex. blue crab – found in NYS, more common in Chesapeake region; predators and scavengers Ex. Uca fiddler crabs (M has 1 small claw, 1 large claw) Ex. Pagurus – hermit crabs (will find and inhabit shells to use) Ex. Eremitus – mole crab, burrow into sandy beaches Ex. spider, decorator and king crabs (huge) Ex. Isopoda, aquatic and terrestrial – potato bug, slater, and pill bugs (Armadillidium), sea lice Ex. Gammarus – sideswimmer or scud Deuterostomes – share same type of embryonic develplemnt radial cleavage Phylum Echinodermata (spiny skin) 2006sequenced genome of purple sea urchin discovered hemichordates and echinoderms are sister groups to chordates Body Plan pentamerous (5fold) radial symmetry as adults great fossil preservations due to very tough exteriors larvae are bilaterally symmetrical internal calcareous skeleton (often spiny, has projections) move about using water vascular system (tube feet); also used in respiration and feeding nervous system often in a ring, with radial nerves to legs (simple design but relatively well coordinated) no excretory organs Life Cycle most have males and females; external fertilization (release of egg and sperm to fertilize in open water) = planktonic larvae rare asexual forms all marine and almost all benthic, many seen near (rocky) shores no known parasitic species Class Crinioidea – sea lilies and feather stars sessile attached to 1 spot on surface main part of body supported above substrate (stalk) Clas Asteroidea – sea stars, starfish no sharp distinction between arms and body anus on top, mouth usually towards substrate move with tube feet, stiff and slow eat mollusks (bivalves) by inverting stomach into prey and digesting them Ex. Acanthaster (crown of thorns) starfish that eat coral polyps *El Nino event has led to one the worst bleaching events seen in the Great Barrier Reef in several decades Class Ophiuroidea – brittle stars and serpent stars (1900 extant species) arms set off from central disc, can move around more rapidly than sea stars internal skeleton is plates moved by muscles no anus (1 opening to digestive cavity) can filter feed, scavenge or predate Class Echinoidea – sea urchins, sea dollars skeleton made of interlocking plates urchins covered with moveable spines (softer in sand dollars) Mouth has 5 teeth of calcium carbonate – see Aristotle’s lantern most urchins scrape surfaces, eat algae or sessile animals Class Holothuroidea – sea cucumbers eaten in Asia long, wormlike 5rows of tube feet run from mouth to anus Ossciles – reduced skeletal plates feeding tentacles around mouth Human Uses keystone grazers (urchins) and predators (sea stars) larvae used in deuterostome developmental biology eaten by human and sea otters (otters helpful in keeping urchins in check, see kelp forests) some make toxins used in pain medication Phylum Hemichordata (~120 species) marine worms closest living relatives to chordates dorsal extension of pharynx form anterior buccal tube most are filter feeders, burrow in sediment Phylum Chordata Subphylum Urochordata (Tunicata) – tunicates, ~12502000species includes salps and other groups Body Plan covered with polysaccharide tunicate coat of cellulose (not bony) Habitat and Ecology sea squirts filter water can be colorful can be solitary or colonial siphons point away from substrate Larvae free swimming with chordate characteristics swim, attach to substrate, lose mobility and nervous system degenerates as they mature to adult form Ex. Oikopleura – lives in mucous hose, creates current by beating its tail (often 35mm) Subphylum CephalochordataAmphioxus benthic, marine, somewhat fishlike ‘lancelets’, bladelike appearance can reach 5000 individuals/square meter