Two congeners with distinct genetic signatures Predicting range shifts in the Arctic zooplankton: On the distribution and genetic connectivity of Themisto amphipods Charlotte Havermans 1,2 , Wilhelm Hagen 1 , Christoph Held 2 , Holger Auel 1 1 Marine Zoology, Bremen Marine Ecology (BreMarE), Universität Bremen 2 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven [email protected] « Arctic wanderers » Zooplankton sampling during Polarstern expedition PS107 to Fram Strait in 2017 References: 1. Auel H, Werner I (2003) J Exp Mar Biol Ecol 296: 183-197 2. Dalpadado P (2002) Polar Biol 25: 656-666 3. Auel H, Harjes M, da Rocha R, Stübing D, Hagen W (2002) Polar Biol 25: 374-383 4. Kohlbach D, Graeve M Lange BA, David C, Peeken I, Flores H (2016) Limn Ocean 61: 2027-2044 5. McNicholl DG, Walkusz W, Davoren GK, Majewski AR, Reist JD (2016) Polar Biol 39: 1099-1108 6. Lønne OJ, Gabrielsen GW (1992) Polar Biol 12: 685-692 7. Nilssen KT, Haug T, Potelov V, Timoshenko YK (1995) Polar Biol 15: 485-493 8. Marion A, Harvey M, Chabot D, Brêthes JC (2008) Mar Ecol Progr Ser 373: 53-70 9. Volkov AF (2012) Russ J Mar Biol 38:7-15 10. OBIS (2018) Distribution records of Themisto libellula and T. abyssorum. Available: Ocean Biogeographic Information System. Intergovernemental Oceanographic Commission of UNESCO. www.iobis.org. Accessed: 2018-01-03. Funding : German Science Foundation (DFG) Project HA 7627/1 - 1 Arctic macrozooplankton sampling Towed bongo net Multinet: few animals but depth stratification Bongo net: shallow (ca. 40 m) and deep (ca. 150 – 310 m) tows shallow tow: nets equipped with two GoPro ® cameras Polarstern expeditions PS100 (2016) and PS107 (2017) Fram Strait and Greenland shelf Tree & haplotype networks Cytochrome c oxidase I gene (COI) Sampling sites & regions T. abyssorum T. libellula T. compressa 99 99 N=132 N=49 N=100 N=21 N=10 Top left: Sampling map with different stations sampled with plankton nets during PS100 and PS107 from which specimens were used for molecular analyses. Bottom left: Neighbour- Joining Tree based on pairwise distances (p) with bootstrap support (Nreps = 2000) for the three species sampled: T. libellula (132 specimens), T. abyssorum (49 specimens) and T. compressa (1 specimen). Right: Haplotype networks (parsimony, 95% probability threshold) with the colours representing sampling regions, referring to the coloured rectangles on the map. The areas of the circles are proportionate to the frequencies of the haplotypes in the sampling. Black nodes represent hypothetical or ‘missing’ haplotypes and each line a single substitution. Distributional patterns 045 002 038 007 034 032 031 021 030 028 029 T. libellula T. abyssorum Map with Bongo net stations of PS107 and the different proportions of T. libellula and T. abyssorum caught in both shallow and deep tows. Themisto abyssorum Abundances varying from 0.003 ind.m -3 (St 031) – 0.506 ind.m -3 (St 002) - Abundant in deeper waters within West Spitsbergen Current (WSC) or Return Atlantic Current. - Also present in shallow Bongo tow samples, indicating presence in colder waters. Themisto libellula Abundances varying from 0.007 ind.m -3 (St 045) – 2.178 ind.m -3 (St 002) - High abundances compared to literature (Fram Strait, Greenland shelf 1 ) - Both in 40m and 300m tows - Highly abundant in stations influenced by the warmer WSC (e.g. St 002, St 034) - Less abundant in western Greenland shelf stations and in very low numbers on the Svalbard shelf. Who is where & how are populations connected? Occurrences, vertical distribution & abundances Population structure: Length-frequency distributions Connectivity: molecular analyses of different populations Vertical distribution and population structure Images of swimming T. libellula from the underwater recordings, Recordings show that T. libellula does not form swarms in the water column Outlook: what’s next? How tightly are the two species linked to the different water masses? Thermal acclimation and resilience of T. abyssorum vs. T. libellula Whole-transcriptome profiling of amphipods exposed to thermal stress to assess their ecophysiology and predict the effects of warming waters R/V Polarstern Atlantic vs. Arctic species in a scenario of Atlantification: Themisto as case study Themisto libellula Themisto abyssorum Both species High biomass Swarming (?) Carnivorous Opportunistic (?) Overlapping distributions Some aspects of their biology understudied, genetic structure unknown Deeper layers Boreal-Atlantic 1-2 year life-cycle 1,2 smaller Pelagic trophic pathway 3,4 Arctic Epipelagic layer Important resource for Arctic marine vertebrates 5,6,7 Cryo-pelagic trophic pathway 3,4 – ice-dependent 2-4? year life-cycle 1,2 bigger Less valuable resource for Arctic marine vertebrates OBIS OBIS Expected range expansion Expected range retraction but recent new occurrences in Southern Bering Sea and Gulf of St Lawrence 8,9 Consequences for food web & biogeochemical cycles? Likelihood of range shifts? the Multinet Size structure within species varies according to site… St 038 N = 73 …and according to depth at the same site St 007 N = 592 N = 310 St 034, 0-40 m St 034, 0-300 m N = 116 Length distributions of T. libellula (blue bars) and T. abyssorum (red bars) at selected stations. A closer look at the different findings will allow to identify fine-scale population structure - varying along a bathymetric and geographic gradient, - influenced by local hydrography Themisto abyssorum Size from < 1 mm to 1.8 cm Themisto libellula Size from 2.5 mm to 3.3 cm Newly hatched juveniles present for both species Mean sizes of Themisto species known to vary according to water masses 2 Themisto abyssorum High haplotype diversity Genetic heterogeneity – even between specimens from the same station Depth stratification, aggregation between sexes? - Morphological investigations of specimens, - Comparison genetic structure with exact depth occurrences Higher dispersal capacities linked to behaviour or hydrography? Themisto libellula Low haplotype diversity: 1 dominant one Genetic homogeneity – between stations on the Greenland Shelf & Fram Strait Distinct historical events? Higher degree of local adaptation??? Identical haplotypes across large distances and temperature range (-1°C – 5°C) Higher plasticity??? Now on Youtube! Admixture of divergent lineages from different regions? Fram Strait
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Two congeners with distinct genetic signatures
Predicting range shifts in the Arctic zooplankton: On the distribution and genetic connectivity of Themisto amphipods
Charlotte Havermans1,2, Wilhelm Hagen1, Christoph Held2, Holger Auel1
1Marine Zoology, Bremen Marine Ecology (BreMarE), Universität Bremen2Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven
« Arctic wanderers »
Zooplankton sampling during Polarsternexpedition PS107 to Fram Strait in 2017
References:1. Auel H, Werner I (2003) J Exp Mar Biol Ecol 296: 183-197 2. Dalpadado P (2002) Polar Biol 25: 656-666 3. Auel H, Harjes M, da Rocha R, Stübing D, Hagen W (2002) Polar Biol 25: 374-383 4. KohlbachD, Graeve M Lange BA, David C, Peeken I, Flores H (2016) Limn Ocean 61: 2027-2044 5. McNicholl DG, Walkusz W, Davoren GK, Majewski AR, Reist JD (2016) Polar Biol 39: 1099-1108 6. Lønne OJ,Gabrielsen GW (1992) Polar Biol 12: 685-692 7. Nilssen KT, Haug T, Potelov V, Timoshenko YK (1995) Polar Biol 15: 485-493 8. Marion A, Harvey M, Chabot D, Brêthes JC (2008) Mar Ecol Progr Ser 373:53-70 9. Volkov AF (2012) Russ J Mar Biol 38:7-15 10. OBIS (2018) Distribution records of Themisto libellula and T. abyssorum. Available: Ocean Biogeographic Information System. IntergovernementalOceanographic Commission of UNESCO. www.iobis.org. Accessed: 2018-01-03.
Funding: German Science Foundation (DFG)
Project HA 7627/1-1
Arctic macrozooplankton sampling
Towed bongo net
Multinet: few animals but depth stratification
Bongo net: shallow (ca. 40 m) and deep (ca. 150 – 310 m) tows
shallow tow: nets equipped with two GoPro® cameras
Polarstern expeditions PS100 (2016) and PS107 (2017)
Fram Strait and Greenland shelf
Tree & haplotype networksCytochrome c oxidase I gene (COI)
Sampling sites & regions
T. libellula
PS107TabC148
T. abyssorum
T. libellula
PS107TabC148
T. abyssorum
T. abyssorum
T. libellula
T. compressa
99
99
N=132
N=49
N=100 N=21
N=10
Top left: Sampling map with different stations sampled with plankton nets during PS100 and PS107 from which specimens were used for molecular analyses. Bottom left: Neighbour-Joining Tree based on pairwise distances (p) with bootstrap support (Nreps = 2000) for the three species sampled: T. libellula (132 specimens), T. abyssorum (49 specimens) and T.compressa (1 specimen). Right: Haplotype networks (parsimony, 95% probability threshold) with the colours representing sampling regions, referring to the coloured rectangles on themap. The areas of the circles are proportionate to the frequencies of the haplotypes in the sampling. Black nodes represent hypothetical or ‘missing’ haplotypes and each line a singlesubstitution.
Distributional patterns
045
002
038
007
034
032031
021
030
028
029
T. libellula
T. abyssorum
Map with Bongo net stations of PS107 and the different proportions of T. libellula and T. abyssorum caughtin both shallow and deep tows.
Themisto abyssorum
Abundances varying from0.003 ind.m-3 (St 031) – 0.506 ind.m-3 (St 002)
- Abundant in deeper waters within West SpitsbergenCurrent (WSC) or Return Atlantic Current.- Also present in shallow Bongo tow samples, indicatingpresence in colder waters.
Themisto libellula
Abundances varying from0.007 ind.m-3 (St 045) – 2.178 ind.m-3 (St 002)
- High abundances compared to literature(Fram Strait, Greenland shelf1)- Both in 40m and 300m tows- Highly abundant in stations influenced by the warmer WSC (e.g. St 002, St 034)- Less abundant in western Greenland shelf stations and in very low numbers on the Svalbard shelf.
Who is where & how are populations connected?
Occurrences, vertical distribution & abundances
Population structure: Length-frequency distributions
Connectivity: molecular analyses of different populations
Vertical distribution and population structure
Images of swimming T. libellula from the underwater recordings,
Recordings show that T. libellula does not formswarms in the water column
Outlook: what’s next?
How tightly are the two species linked to the different water masses?
Thermal acclimation and resilience of T. abyssorum vs. T. libellula
Whole-transcriptome profiling of amphipods exposed to thermal stress to assess their ecophysiology and predict the effects of warming waters
R/V Polarstern
Atlantic vs. Arctic species in a scenario of Atlantification: Themisto as case study
Themisto libellulaThemisto abyssorumBoth species
High biomassSwarming (?)
CarnivorousOpportunistic (?)
Overlappingdistributions
Some aspects of theirbiology understudied,
genetic structure unknown
Deeper layers
Boreal-Atlantic
1-2 year life-cycle1,2
smaller
Pelagic trophicpathway3,4
Arctic
Epipelagic layer
Important resource for Arcticmarine vertebrates5,6,7
Cryo-pelagic trophic pathway3,4
– ice-dependent
2-4? year life-cycle1,2
bigger
Less valuable resource for Arcticmarine vertebrates
OBISOBIS
Expected range expansion Expected range retractionbut recent new occurrences in Southern Bering Sea
and Gulf of St Lawrence8,9
Consequences for food web & biogeochemical cycles?
Likelihood of range shifts?the Multinet
Size structure within species varies according to site…
St 038N = 73
…and according to depth at the same site
St 007N = 592
N = 310
St 034, 0-40 m St 034, 0-300 mN = 116
Length distributions of T. libellula (blue bars) and T. abyssorum (red bars) at selected stations.
A closer look at the different findings will allowto identify fine-scale population structure - varying along a bathymetric and geographic
gradient, - influenced by local hydrography
Themisto abyssorum
Size from < 1 mm to 1.8 cm
Themisto libellulaSize from 2.5 mm to 3.3 cm
Newly hatched juveniles present for bothspecies
Mean sizes of Themisto species known to vary accordingto water masses2
Themisto abyssorum
High haplotype diversity
Genetic heterogeneity– even between specimens fromthe same station
Depth stratification, aggregation between sexes?
- Morphological investigations of specimens, - Comparison genetic structure with exact depth occurrences
Higher dispersal capacities linked to behaviour or hydrography?
Themisto libellula
Low haplotype diversity: 1 dominant one
Genetic homogeneity– between stations on the Greenland Shelf& Fram Strait
Distinct historical events?
Higher degree of local adaptation???
Identical haplotypes acrosslarge distances and
temperature range (-1°C – 5°C)
Higher plasticity???
Now on Youtube!
Admixture of divergent lineagesfrom different regions?
Fram Strait
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