Post on 13-Oct-2020
Karen H. Beard9 February 2008
Population density, diets, and growth rates of Eleutherodactylus coqui in Hawaii
Beard et al. (In Review) J. of Herpetology
2,954 adults in 8 study plots over 3 years
°N 19
°N 20
0 50 10025Kilometers
H A W A I I
Kailua
Hilo
OL
AK
PK
HSPP
LT
MPH a w a i i a n I s l a n d s
Hawaii
Maui
OahuKauai
KP
Population Estimates
Sex, SVL, Habitat, Color pattern, Individually mark5-9 nights, 60% recap
Woolbright (2005) Herp. Review
Year
2004 2005 2006
Abun
danc
e Es
timat
e (A
dults
/ha)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000Akaka FallsHumane SocietyKalopa State ParkLava TreeManuka NARWaipio OverlookPuanaikoParadise Park
°N 19
°N 20
0 50 10025Kilometers
H A W A I I
Kailua
Hilo
OL
AK
PK
HSPP
LT
MPH a w a i i a n I s l a n d s
Hawaii
Maui
OahuKauai
KP
• Lava Tree had a 3-yr mean 3X higher than the highest long-term mean from Puerto Rico.
2x
3x
Beard et al. (Accepted) J. of Herpetology
Adult density estimates
2X
Preadult:Adult Total Density (Frogs / ha)2004 2005 2006 2004 2005 2006 Mean10.86 2.64 5.55 74,700 18,900 25,500 39,7002.00 2.27 1.35 21,600 23,500 20,400 21,800
-- 2.97 0.36 -- 2,400 2,000 2,2001.43 2.27 2.97 32,300 32,700 40,500 35,2005.62 0.57 2.21 91,400 8,500 -- 49,900*
0.24 1.17 0.20 2,600 3,100 3,000 2,9001.84 1.27 2.05 15,100 12,900 22,900 17,0002.76 -- -- 35,300 -- -- 35,300
Total density estimates Preadult:adult x adult estimate = preadult estimate
Site
AKHSKPLTMPOLPKPP
Before Hurricane Hugo 1989 After Hurricane Hugo 1990Woolbright (1996) Biotropica, Stewart & Pough (1983) Science
What limits coqui densities?
Positive relationship between total density and habitat structure across study sites
Habitat Structure in the Understory
10 20 30 40 50 60 70 80 90
Tota
l Fro
g D
ensi
ty /
ha
0
10000
20000
30000
40000
50000
60000
AK
HS
KP
LT
MP
OL
PK
R2 = 0.85 F = 28.42, P < 0.01
Waipio (OL)
Manuka (MP)Beard et al. (Accepted) J. of Herpetology
Weak positive relationship between invertebrate abundance and total density across study sites
Beard et al. (Accepted) J. of Herpetology
Invertebrate Abundance
20 40 60 80 100 120 140 160 180 200T
tlF
Dit
/h
0
10000
20000
30000
40000
50000
60000
AK
HS
LT
MP
OL
PK
PP
R2 =0.45 F = 4.04, P = 0.10
Sin et al. 2008 Biological Invasions
Ecological Effects of the Coqui in Hawaii
157°W
157°W
156°W
156°W
155°W
155°W
19°N 19°N
20°N 20°N
21°N 21°N0 50 10025
Kilometers
H A W A I I
M A U I
H a w a i i a n I s l a n d s
Hawaii
Maui
OahuKauai
MMG
MKN
OL
AKPK
KCPP
MP
HS
LT
KT
Frog Stomach Content Analyses
11 study sites, Summer 2004
Beard 2007 Copeia
Orders
Acarina
AmphipodaAraneae
Coleoptera
CollembolaDiptera
Frog eggs
Hymenoptera-antsIsopoda
Per
cent
of S
tom
ach
Con
tent
s by
Item
0
10
20
30
40
50
60
No:CulicidaeDespite:Tipulidae
Beard 2007 Copeia
696 frogs, 5310 invertebrates were identifiable. 7.6 ± 7.6 (SD) prey items per stomach.
Males: 0.008 ± 0.0007 vs. 0.02 ± 0.0003Females: 0.01 ± 0.001 vs. 0.08 ± 0.005
Controlled for SVLWoolbright (1985) Copeia
Growth rates
• Is fitness higher in Hawaii or Puerto Rico?
• Common environment• 4 Puerto Rico populations
and 2 Hawaii populations• Fitness measures:
– Number of eggs per clutch?– Egg size?– Offspring size?– Growth/survivorship of
offspring?
E.M. O’Neill
Range
Hawaii Puerto Rico0.000
0.005
0.010
0.015
0.020
0.025
0.030
RangeHawaii Puerto Rico
Ht
hliS
0
2
4
6
8
Range
Hawaii Puerto Rico
Ei
(
0
1
2
3
4
5
6
7
F1,27 =1.38, P = 0.25 F1,27 =12.68, P = 0.0014
F1,27 =6.89, P = 0.014
*
*
F1,27 =6.90, P = 0.015
*
RangeHawaii Puerto Rico
0
10
20
30
40
Velo-Antón et al. (2007) Molecular Phylogenetics and Evolution
Peters et al. (2008) Molecular Ecology Notes
• Thirteen microsatellite loci were isolated from the coqui frog
• The purpose for initiating this study was to determine the number of introductions in Hawaii and the primary source or mode of introductions
LT
Peters et al. (2008) Molecular Ecology Notes
Bayesian population assignment test
Hawai Data
LT
• Coqui densities vary across sites, but can be 3X higher than Puerto Rico
• Habitat structure is highly correlated with coqui densities
• Coquis are mostly consuming non-native leaf litter invertebrates, esp. ants, amphipods
• Two introductions• Extreme bottleneck
Conclusions
Funding Sources and Support: Jack Berryman Institute
US Fish and Wildlife ServicesHawaii Land and Natural Resources (Invasive Species Council)
USDA/APHIS/WS Hilo Field StationUtah State University
William C. Pitt for logistical supportMISC, KISC and OISC for sending frog samples
Graduate students: Hans Sin, Nathania Tuttle, Eric O’Neill,
Simon Bisrat, Emily PriceUndergraduate students:
Kody Crowell, Jesse Poulos, Dixon Grant, Michelle Higashi, Austin Huff, Ray McGuire, and others