BIOLOGIA GENERALE 14 dicembre 2007

Transcript

1 BIOLOGIA GENERALE 14 dicembre 2007 dispense basate su quelle della Prof.ssa Laura Beani e del Prof. Francesco Dessì Facoltà di Psicologia Tecniche di Psicologia Generale e Sperimentale Alessandro Massolo Dip. Biologia Animale e Genetica c/o Prof. F. Dessì-Fulgheri (Via Romana 17) massolo@unifi.it Massolo Alessandro massolo@unifi.it; Tel

2 Differenza nell investimento parentale

3 Facoltà di Psicologia Scelte sociali complesse

4 Cure e investimento parentali Parental Care (PC) -- Any form of parental behavior that appears likely to increase the fitness of a parent's offspring Parental Investment (PI) -- Any form of parental behavior that increases an individual offspring's fitness at the cost of the parent's ability to invest in future offspring. (Trivers, 1972)

5 II. PARENTAL INVESTMENT TYPES 1. Before Birth A. Investment in gamete production Ex. female katydids who consume spermatophores provided by males have larger eggs which survive overwintering better (male investing in females gametes) B. Preparation of the environment -- Ex. preparation of nests, burrows, or territories (importance of having a place where broods or eggs can be keptwhere young can be left while parents forage or ward off predators) bees, fish, birds C. Care of fertilized eggs -- Ex. Placentas, incubation by birds, egg guarding by fish, carrying brood by waterbugs and seahorses, protection of nest sites or sites where eggs are laid 2. After Birth A. Provisioning or protecting young -- Ex. provisioning by birds, brooding fry in mouth in some fish, lactation in mammals B. Care following nutritional independence -- Ex. support in conflicts in social primates. Feeding some species of birds after they have left the nest (royal terns or frigate birds)

6 Male & female investment in reproduction (Trivers 1972): Parental investment = any behavior toward offspring that increases the chances of the offspring's survival at the cost of the parent's ability to invest in future offspring. Males & females - both selected for producing the number of offspring that results in maximum reproductive success Reproductive success = not measured simply by number of offspring but by difference between number of offspring (benefits) & decreased reproductive potential in the future because of present offspring (costs) Females often invest more in each offspring & their investment curve tends to rise more quickly (shown below). As a result, males & females may disagree about the optimum number of offspring &, as a result, males in many species will seek access to additional females. Such behavior leads to greater competition & selection.

7 Barash 1982 (Figure 10.3, p. 219) Facoltà di Psicologia

8 Modalità di fecondazione e cure parentali Facoltà di Psicologia

9 Evoluzione delle cure parentali negli uccelli di ripa (Scolopacidae)

10 Ipotesi sul sesso che effettuerà le cure parentali 1. The investment hypothesis Female invests so much energy, it would be risk for her to abandon her offspring without providing care, since offspring may not survive. 2. The paternity uncertainty hypothesis Female more likely to be parent of offspring than male - male not really gaining from parental care if offspring not his. Better strategy for male to seek additional matings elsewhere. 3. The order of gamete release hypothesis Patterns of parental care result from differences in the opportunities for males and females to desert offspring. Internal fertilization -- Situation enables males to desert (females more likely to hold the fertilized eggs). Female then forced to provide PI. (But if fertilization is external females can turn roles around and desert). Exceptions -- Simultaneous gamete release across species of fish does not hold up hypothesis (male still provides the care in most species). Also, male care is common in frogs who release sperm in nest before females deposit egg. 4. The association hypothesis Females more likely to be the parent around during egg laying or birth. Males may not be around during this phase. Males physically separated from progeny. Exceptions -- Also makes sense with internal fertilization, but not with external fertilization with simultaneous release of gametes (again predicts 50/50 but majority of care is by male)

11 Le cure parentali nel modo animale Facoltà di Psicologia 1. Terrestrial Arthropods A. PC is uncommon B. Care by females much more common than care by males E.g. of care - Carry brood on back (Scorpions, spiders), provide food for larvae 2. Reptiles A. PC is uncommon B. Care by females more common E.g. Crocodilians. Males and females respond to calls of hatchlings they hatch underground and vocalize- parents dig them up and bring them to water in mouth wash them. 3. Amphibians A. 18% salamanders and 6% frogs and toads exhibit some sort of parental care B. Care by males or females E.g. egg attendance and transport, tadpole attendance and transport, tadpole feeding. 4. Fish A. At least 25 % of fish demonstrate parental care B. Male care more common than female care E.g. of care: egg guarding, oral brooding, cleaning eggs 5. Birds A. Most species show biparental care E.g. of care includes provisioning of female by male prior to and during egg laying and incubation, nest building, incubation of eggs, feeding nestlings 6. Mammals A. 100% of species show care by females (gestation, lactation) B. Less than 5% show direct male care male care mostly in monogamous breeders (e.g. tamarins, wolves, naked mole rats E.g. feeding, transport, protection from predators

12 Cure parentali: associazione con i piccoli? Facoltà di Psicologia

13 Dimensioni corporee e successo riproduttivo nei pesci

14 Costo delle cure parentali Facoltà di Psicologia Sarotherodon galilaeus

15 Cure parentali maschili negli emitteri acquatici

16 Presenza del compagno e successo riproduttivo in Nicrophorus orbicollis

17 Cure parentali e riconoscimento della prole

18 Facoltà di Psicologia Riconoscimento della prole