Juvenile vs. adult environments Transgenerational environmental effects

1. Juvenile vs. adult environmentsTransgenerational environmental effects

2. Genetic and phenotypic inheritance

3. Definitions Genetic adaptation- direct role of the genome- in stable and unstable environments- speciationHowever: this is not the whole story! Phenotypic plasticity- one genotype  several genotypes- poorly understood- present and past influences

4. Definitions Transgenerational effects- transferred over several generations- environmental effects- phenotypic or genotypic Maternal effects- explanation for phenotypic plasticity- a non-genetic variation

5. Maternal Effects How much to invest in offspring - Mothers decide- based on experiences (life history) - environmental cues (stable and unstable environment)Crucial for the phenotype and its survival, life history. A key role in population dynamics- causes for population fluctuation- organism – environment interactions (density)- factor in predictive population modelling

6. Metabolic Imprinting Metabolic condition- is often not optimal- transferred from parents to offspring- can be stable over generations Consequences- e.g. disability to allocate nutrients- bad conditions hold greater risk- long term effects

7. The Difficulties Variation in phenotype due to genetic effects or phenotypic plasticity? Importance to know about genetic effects in order to rule them out!

8. Adults – an emphasis on non-genetic influences

9. 1. Why only Maternal Effects? Characteristics- mothers have the responsibility over the offspring- mRNA, mitochondria, cellular fluids are maternal Mothers decide through- environmental cues- her own state- her life history how to equip the young (embryo, eggs)

10. 2. Influences of the Environment Stable environments- the mother uses current cues- current environment- problems Unstable environments- the mother uses current and past cues- future environment Cyclic environments- negative maternal effects- also problems

11. 2. Influences of the Environment Environmental cues- temperature- photoperiod- problems- food availability The environment  mother  state of the young in development.

12. Example: Insects -environmental influences on oviparous invertebrates

13. Insects: Influences on Diapause Reason- individuals survive reoccurring adverse environments (drought, extreme temperatures, food shortage) Types- obligate diapause- facultative diapause (maternal effects) Environmental cues- photoperiod and decreasing temperatures- the age of the mother  adjustment of egg content

14. Insects: Influences on Dispersal The nature of the dispersal trait- to fly or not to fly  change of the flight polymorphism- two different morphs possible Short-winged morph – non-dispersing- stable environment (food source long lived, temperature, population density) Long-winged morph - dispersing- unstable environment (suboptimal factors  food source short lived)- But: wings are costly

15. Insects: Influences on Dispersal Important environmental cue: crowding- depends on population density and the host plant- not always the same amount of individuals needed  depends on food source and species on it The host plant- ephemeral plant or long lived Grasshoppers- swarming or non-swarming phenotype- takes several generations (early transgenerational effects)

16. Insects: Influences on Dispersal Difference in reaction time: genetic Change of juveniles to a different morph:environmental, maternal effects

17. Insects: Influences of the Host Plant Settlement decisions- oviposition Food quality and nutritional problems- optimal host not available- differences in foliage quality

18. Insects: Influences of the Host Plant The optimal plant is C. floridium. S. limbatus survives better on this plant than on the two but is adapted to all three plants.

19. Insects: Influences of the Host Plant State of the host plant- state of the mother  state of the eggs- host diet influences- dispersal influences Quality of the diet- microorganisms detoxify allochemicals- microorganisms provide essential nutrients- toxins (pollution, human insertion)  intestine samples

20. Example: Lizards – environmental influences on viviparous vertebrates

21. Characteristics of Vivipary Viviparous mothers- influence young throughout their entire development- more control- better survival- ensure better shielding from external environment - but: they have a greater cost - greater influence of maternal effects- maternal conditions (or parental) play a greater role

22. Lizards: Experiment Methods Characteristics of the organism- scincid lizard Niveoscincus ocellatus- natural basking behaviour- change in temperature  influence on the young- change of basking (light, heat) artificially- poikilothermic  basking influences metabolism and fitness In the wild- same species, different habitats, different light and temperature regimes- different phenotypic morphs

23. Lizards: Experiment Results Influence on the physiology of the young- longer basking  young were bigger, faster growth- less vulnerable to predation- fast at reproduction period Viability of the young- longer basking  always gave birth- shorter basking  death of a female, abortion Performance of the young- racing experiment

24. Lizards: Experiment Conclusions Parturition dates- overlapped with those in the wild- long basking with good environments- short basking with worse environments Gestation length- temperature dependant- accelerated growth and metabolism

25. Lizards: Experiment Conclusions Adaptation to a broad range- all clutches are viable- different habitats  different phenotype- mother shelters embryo from harsh environment- mothers body temperature variable  lower in bad habitat (selection for high  cost) Low temperatures- more energy to cell maintenance- less to growth  Variation due to phenotypic plasticity?

26. Lizards: General Conclusions Annual and geographic thermal variations are important for development of young. Mechanisms are largely unknown. Variation results in long term benefits or constraints.

27. 3. Juvenile and Adult Habitats Juvenile habitat- is different from the adult one- has a less broad range  adaptive adjustments- influences decisions and adjustment of the offspring by the adult Adult habitat- will have no influence on the adjustment of the offspring- no matter if the conditions are good or bad

28. Example: Fish – juvenile environments of mothers take influence

29. Fish: Methods and Results The organism and the methods- Simochromis pleurospilus, a lake Tanganika cichlid- four different experimental groups- mass of the clutches was calculated Results- low juvenile diet mothers  larger offspring- not explained by extended brood care- no worse condition  no compensatory effect- growth dependant on yolk reserves- eggs have a higher mass

30. Fish: Experiment Results There is only a difference between mothers that have been raised under different diet regimes in the juvenile phase.

31. Fish: Experiment Results Adults occur in deeper water than the young and have a different diet regime. The quality of the young thus has to be adjusted to the adults juvenile environment.

32. Fish: Conclusions Poor diet females boost offspring size- by producing eggs with a higher energy content- young grow faster  use external food resources General conclusions- large offspring better in adverse environments- smaller offspring better in better environments • Mothers of poor juvenile habitat experience equip their young better • Juvenile stage in an indicator for non-genetic adaptation

33. Eggs and eggs size

34. Egg Size Small eggs- good quality environment (food)- many eggs (trade off)- less long to hatch (external food source)- grow and mature slower (smaller at hatching  bad in bad conditions) Large eggs- bad quality environment (bigger protein load)- fewer or only one egg laid- faster growth- prolonged stay in eggs, less long development out side (less vulnerable)

35. General Comments about Eggs Genotypic influence- independent of environment- same environment, different eggs Environmental influence- good environment  egg size doesn’t matter- bad environment  big eggs, more provision Adaptation- better adaptation of those that can lay smaller and bigger eggs  broader ranger of phenotypic plasticity- but their smaller eggs are less adapter to good environments

36. Juveniles – a focus on compensation strategies

37. 1. Environmental Effects Effects of the environment of the juvenile parent- alter the parents perception of how to invest in offspring- influence of preceding generation Juveniles not always optimally adapted- miscalculation of the parents- forced to live in suboptimal environment- worse parental genetic quality  Bad start

38. 2. The Bad Start Reasons- insufficient time or to acquire resources- insufficient quantity of resources A mother’s allocation is bad- fewer nutrients are allocated- problems with species with an extended egg stage- per-natal exposure to famine (in humans)  obesity, diabetes

39. 2. The Bad Start More reasons- juveniles born late in the season (environmental conditions, bad habitat)- born later in a clutch (growth competition)- differences in sex (faster growing sex)- sensitive periods  non-genetic effects (nutrition) or genetic effects?

40. 3. Compensatory Strategies Nutritional condition strategies- in key phases of development- affects juveniles- bad environment  slow growth and development- better environment  accelerated growth • Costs and fitness disadvantage

41. 3. Compensatory Strategies The nature of the costs- depend on the nature of the deficit, the reason and its timescale- what mechanisms get affected?- compensation cannot be too costly- paid over a range of time scales (physiology, cells)- trade off with another trait (butterfly, caterpillar) • bad phenotype: bad start or compensation? • cost are not always paid right away!

42. 3. Consequences Lesser cell number- fewer cells per organ- fewer units in an organ- higher work load of one unit or one cell- less long viability  Example: human kidney More energy for physiological processes- organs of low quality  more metabolic processes- for this compensation more energy per organ used

43. 3. Examples For compensation to occur- benefits of this stronger that momentary and future costs- better fitness prospects Accelerated growth- normally: growth rate at an optimum- all else is costly- limited to a period of life- differences between sexes- not always possible (depends on environmental state)- irreversible effects

44. 3. Examples Faster transition between developmental stages- earlier stages are less long- less long in sensitive stages  evasion- examples: tadpole, holometabolic insects Difference in cell number between organs- “brain sparing”, sparing of reproductive organs- focus on the organ that will ensure the most fitness benefit even in a bad condition

45. Thank you!