Stable Isotopes and Animal Migra4on. February 24, 2010

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1 Stable Isotopes and Animal Migra4on February 24, 2010

Outline: 1. Using isoscapes to track animal migra4on a quick review. 2. Examples: 1. 2. 3. 4. African elephants Cerling et al.

2 Outline: 1. Using isoscapes to track animal migra4on a quick review. 2. Examples: African elephants Cerling et al., 2009, PNAS Sockeye Salmon Finney et al., 2002, Nature American Redstarts Norris et al., 2004, Science Bats in the eastern US Britzke et al., 2009, Journal of Mammalogy

3 Three Principles of isotopic tracking: 1. The isoscape terrain through which the animal of interest moves must be known. 2. Isotopic values in animals can be offset from base line isoscape values due to isotopic discrimina4on and such discrimina4on factors need to be known for the 4ssue of interest. 3. The 4me period of spa4al integra4on corresponding to a par4cular animal 4ssue needs to be known. Hobson et al., 2010

4 C3/C4/CAM (δ 13 C, δd): Red winged Blackbird Example: Study showed strong segrega4on between two groups of Red winged Blackbirds clearly related to corn consump4on in agricultural areas. Authors further associated those corn areas with more northern la4tudes in the USA using feather δd values. Wassenaar and Hobson, 2000

δ13c, δd: 1999, Oecologia Stable hydrogen and carbon isotopic composi4ons

diets. δd provides a good indicator of la4tude.

N. America showed a dis4nct pa_ern of enrichment along a SW to NE gradient

5 δ13c, δd: 1999, Oecologia Stable hydrogen and carbon isotopic composi4ons of adult monarch bu_erﬂies closely resemble those of their natal (larval) diets. δd provides a good indicator of la4tude. Stable carbon isotope values in milkweed and bu_erﬂy wings across eastern N. America showed a dis4nct pa_ern of enrichment along a SW to NE gradient bisec4ng the Great Lakes they provided further resolu4on in the determina4on of monarch natal origin.

6 Deuterium and 18 O in Precipita4on and Surface Waters: 2008, PNAS Ehleringer et al. (2008) showed excellent agreement between drinking water δd and δ 18 O measurements and those in human hair across the United States.

7 Stron4um Isotopes ( 87 Sr/ 86 Sr): For some freshwater vertebrates, such as fish, dissolved Sr in water is the primary source of Sr in 4ssues it therefore has great poten4al for tracking where fish travel (but requires that geology is different). Hobson et al., 2010

Isotopic turnover: Important to iden4fy whether or not mul4ple nutrient pools are involved in 4ssue synthesis, but absolute half lives are less important.

8 Isotopic turnover: Important to iden4fy whether or not mul4ple nutrient pools are involved in 4ssue synthesis, but absolute half lives are less important. Note that the one pool model (#2) does the worst job of predic4ng the environment par4cularly for the region where the elephant spends the least amount of 4me. Illustrates the apparent enrichment b/twn diet and 4ssue is different in different environments and is a result of a nonequilibrium condi4on. Hobson et al., 2010

9 Case Studies: Birds and Insects Feathers, wing chi4n both inert following forma4on and provide info about origin. Mammals Claws, hair, hooves, bone collagen. Sequen4al sampling holds great promise. Fish Otoliths

10 Example 1: African elephants 2009, PNAS

Example 1: African elephants MOTIVATION In the face of climate change, it is of interest to trace the rela4onship between elephant diet and vegeta4on change over a long 4me period, par4cularly

11 Example 1: African elephants MOTIVATION In the face of climate change, it is of interest to trace the rela4onship between elephant diet and vegeta4on change over a long 4me period, par4cularly because elephants play such a key role in savanna ecosystems. Previous studies of African savanna elephants show that they prefer grass during the wet season but rely on browse during the dry season. 6 year, temporally fine scale chronology of diet change in an elephant family group using isotopes in tail hair. Cerling et al., 2009

NDVI = Normalized Differen4al Vegeta4on Index High δ 15 N values

12 Example 1: African elephants %C 4 in diet matches fluctua4ons in rainfall and NDVI in the Samburu region. NDVI = Normalized Differen4al Vegeta4on Index High δ 15 N values correspond with high δ 13 C values C 4 plants tend to have a higher δ 15 N value in this ecosystem. Cerling et al., 2009

Changes in dd are more closely synchronized with NDVI demonstrates importance of seasonal rains.

13 Example 1: African elephants Changes in diet d13c track the chronology of NDVI values, but lag by several weeks peak in protein content is likely influen4al to 4ming in dietary switching. Changes in dd are more closely synchronized with NDVI demonstrates importance of seasonal rains. Peak in births will occur 22 months later, at the beginning of the rainy season and just prior to peak grass consump4on. Cerling et al., 2009

14 Example 1: African elephants Cerling et al., 2009

15 Example 1: African elephants CONCLUSIONS Seasonal diet changes are well correlated with changes in NDVI. Dry season δ 13 C values have a baseline value that indicates a diet composed of 5 20% C4 biomass. The peak in grass consump4on occurs ~2 weeks aoer the peak in NDVI. Long term NDVI changes will likely be accompanied by changes in the amount of grass available to elephants during the wet season. Changes in the δd of hair are well correlated with the isotopic composi4on of local drinking water. The minimum value for δd occurs at essen4ally the same 4me as the peak NDVI. Tail hair of wild animals represents an archive of dietary behavior that provides an opportunity to quan4fy diet and the environmental condi4ons experienced by those animals.

16 Example 2: Sockeye Salmon Nature, 2002 Photo Credit: Thomas Quinn

17 Example 2: Sockeye Salmon Oligo meso taxa Oligotrophic taxa

Example 2: Sockeye Salmon The abrupt reduc4on in δ 15 N at 100 BC roughly coincides with a major cultural change associated with transi4on from Early to Late Kachemak.

18 Example 2: Sockeye Salmon The abrupt reduc4on in δ 15 N at 100 BC roughly coincides with a major cultural change associated with transi4on from Early to Late Kachemak. The increase in δ 15 N from AD matches the change from late Kachemak to Koniag period a 4me when human popula4ons rose and began to u4lize more salmon. Frazer Lake serves as a reference lake obstructed by a steep waterfall, it had no salmon before the 1950 s.

Example 2: Sockeye Salmon From AD 300 AD 1200, sardines and anchovies were more abundant when Alaskan sockeye stocks were much weaker than average; this trend is reversed for the past 800 years.

19 Example 2: Sockeye Salmon From AD 300 AD 1200, sardines and anchovies were more abundant when Alaskan sockeye stocks were much weaker than average; this trend is reversed for the past 800 years. Long term trends reported here are dis4nct from the pa_ern seen in historical records sardines covary with salmon but are out of phase with anchovies. Suggests that mul4ple modes of variability in ocean atmosphere circula4on and ecosystem dynamics operate in the N. Pacific.

20 Example 3: American Redstarts Photo Credit: Arthur Morris Science, 2004

Example 3: American Redstarts Important points: Warbler Breeds in Ontario Migrates to the Caribbean Only grow tail feathers once a year (in the fall) 2 Year Study: Year 1) Color band male birds;

21 Example 3: American Redstarts Important points: Warbler Breeds in Ontario Migrates to the Caribbean Only grow tail feathers once a year (in the fall) 2 Year Study: Year 1) Color band male birds; measure parental care males that lost nests to predators didn t have to work as hard (no chicks to feed); track their fall migra4on departure 4me. Year 2) Recapture all returning banded males; pluck tail feathers; measure δd to determine at what la4tude the feather was grown; measure the feather color how orange?

Example 3: American Redstarts RESULTS Birds that did not work as hard the previous year molted before migra4on (δd values were very nega4ve) and were also very vibrantly colored.

22 Example 3: American Redstarts RESULTS Birds that did not work as hard the previous year molted before migra4on (δd values were very nega4ve) and were also very vibrantly colored. Birds that worked hard (i.e. raised chicks) molted during migra4on (δd values were less nega4ve) and were less vibrantly colored. Why would color be less vibrant? Maybe poor food quality? Tired?

Example 4: Bats Goal: To examine δd values of hair in four bat species in the

or la4tude (LAT) and δd hair. Photo: Smithsonian Myo$s sodalis Two queslons: 1.

or δd p based on age or sex? 2. Is there significant interspecific varia4on?

23 Example 4: Bats Goal: To examine δd values of hair in four bat species in the eastern US and test the assump4on of a clear rela4onship between modeled δd precip or la4tude (LAT) and δd hair. Photo: Smithsonian Myo$s sodalis Two queslons: 1. Is there significant intraspecific varia4on in the rela4onship between δd h and LAT or δd p based on age or sex? 2. Is there significant interspecific varia4on? 4 bat species: 1 long distance migrant, 3 regional migrants. Photo: Merlin D. Tu_le Lasiurus borealis

24 Example 4: Bats Found strong rela4onship between dd h and LAT for two species: M sodalis and M. septentrionalis. However, dd p and LAT explain very li_le of the variance in the two other species: M. lucifugus and L. borealis. expect to see the rela4onship between dd p and dd h break down if precipita4on is not the primary source of hydrogen to the food web used by bats (e.g. lake environment) M. lucifugus. expect 4ming and dura4on of molt to also be responsible for blurring the rela4onship between ddh and ddp.

Organism Interactions in Ecosystems

Organism Interactions in Ecosystems Have you ever grown a plant or taken care of a pet? If so, you know they have certain needs such as water or warmth. Plants need sunlight to grow. Animals need food