Baert, Leon

Desender, Konjev

Maelfait, Jean-Pierre

English

Aquatic Commons

20
2) En la Zona del Bosque Siempre Verde (250-800
m), el introducido guayabo (Psídíum guaja va) mostró
un 90% de mortalidad del dosel, pero una alta
capacidad de retoñar de la base. La densa cobertura de
la enredadera Ipamaea alba inhibe en grandes áreas
efectivamente el reestablecimiento del guayabo, lo que
podría beneficiar plantaciones de árboles nativos. En
menores altitudes, la probablemente introducida Tre~
míerantha establece bosques densos (0.5 arboles/m)
pudiendo posiblemente reprimir el guayabo, y/o
volverse una nueva plaga. Sealesía eardata mostró
una numerosa regeneración inicial, hasta que plagas
produjeron una alta mortalidad.
3) En el Bosque Semideciduo (80-250 m),
vegetaciones afectadas por fuegos rápidos limitados al
sotobosque, regeneraron dentro de 2 años; pero áreas
con alta abundancia de jaboncillo (Sapíndus) quemaron
completamente y la regeneración demorará muchos
años.
Los incendios producen cambios vegetacionales a
largo plazo y ayudan a la dispersión de plantas
introducidas. Un alto número de plantas raras mostró
ninguna o sólo baja regeneración dentro de 2 años.
Varias medidas para prevenir y controlar
incendios son indispensables.
LlTERATURE CITED
Anonymous. 1985a. Ordeal by fire and water.
Noticias de Galápagos 41: 1-2.
Anonymous. 1985b. The great fire on Isabela.
Noticias de Galápagos 42:4.
Adsersen, H., and J. Lawesson. 1985. Report on the
activities with permanent vegetation quadrats
on Sierra Negra, Nov. 1985. Mimeographed
Report, Galápagos and Copenhagen.
Gara, R., P. Arnold, J. Peters, and J. Montesdeoca.
1986. El incendio en Isabela: Islas Galápagos.
Estudios Universitarios de la Universidad
Nacional de Loja.
Huttel, C., and A. Winckell. 1985. Los incendios en la
Isla Isabela. Su origen, propagación y
consequencias. Misión ORSTOM, Ecuador.
Márquez, C. 1986. El incendio y la fauna
herpetológica en el sur de la Isla Isabela.
Revista Geográfica del Instituto Geográfico
Militar (24):105-110.
Nowak, J., J. Lawesson, H. Adsersen, and T.A. de
Vries. In press. A two-year study of post-
fire vegetation dynamics on Southern Isabela
Island, Galápagos Islands, Ecuador.
Proceedings of Botany and Management
Workshop in Galápagos.
Vanbeveren, C. 1985. Report on topographic Sierra
Negra recognition. Charles Darwin Research
Station.
Noticias de Galápagos, No. 46, May 1988
J. Bosco Nowak and Jonas E. Lawesson,
Department of Botany, Charles Darwln
Research Statlon, Isla Santa Cruz,
Galápagos, Ecuador.
DISTRIBUTION AND FLlGHT
ACTIVITY OF CARABID BEETLES
GENUS TACHYS IN THE GALAPAGOS
ARCHIPELAGO
By: Konjev Desender, leon Baert, and
Jean-Pierre Maelfait
ABSTRACT
This preliminary report summarizes the results of
recent studies of the carabid beetles belonging to the
genus Taehys in Galápagos. In addition to the two
species previously known to occur in the islands, we
discovered a third as yet unidentified species on the
islands of Santa Cruz and Rábida.
INTRODUCTION
Carabid beetles belong to a very species-rich
beetle family, with worldwide occurrence. Recent
estimates of as many as 50,000 species have been
proposed (N. Stork, pers. comm.). Nevertheless,
many carabids can be characterized by a more or less
similar body form, whereas macromorphological
adaptations would only have occurred to a lesser
degree during their evolutionary history. Despite this
similarity, carabids are found in virtually all
terrestrial ecosystems. Many species show a very
high degree of specialization in their habitat
preference, which seems mainly a consequence of
ecophysiological adaptations, i.e., adaptations to
different microclimatological conditions. Most species
are known to be carnivorous and show a pronounced
soil surface activity, at least during their
reproductive season. Ground beetles show much
variation in their ability to disperse, making them an
excellent group for evolutionary and biogegraphic
studies.
Insects, and terrestrial invertebrates in general,
are among the least studied organisms from the
Galápagos Archipelago. The ecological knowledge of
insects is especially sparse. The carabid beetles of
the genus Taehys have been studied (Van Dyke 1953;
Linsley and Usinger 1966; Reichardt 1976; Franz
1985), but few ecological data exist for these
organisms (Reichardt 1976). The lack of ecological
observations for these beetles may stem in part from
Noticias de Galápagos, No. 46, May 1988
their small size. Adults attain a length of only 2-3
mm.
Until now only two species of Tachys have been
recorded from the Archipelago. Tachys beebei
Mutchler 1925 was described as a species endemic to
the Galápagos, but was subsequently found to be
synonymous with a previously named species, T.
vittiger LeConte 1851, which is widespread along the
western coast of the Americas (Erwin 1974). Within
Galápagos, this species, now known as T. vittiger, has
been collected using light traps on the islands of
Baltra, Seymour, Santa Cruz, and Isabela (cf.,
Reichardt 1976). Tachys erwini Reichardt 1976 is
endemic to the islands and is most closely related to T.
vittiger. It is known from Fernandina and Volcán
Darwin on Isabela. Little is known about the ecology of
this species.
METHODS
During 1982 and subsequently in 1986, we visited
the Galápagos to sample different islands for their
beetle and spider faunas. Our main purpose was to
contribute to the understanding of the distribution,
adaptive radiation, and role of dispersal in the
speciation of carabid beetles. As a preliminary step
we had to consider problems of identification and
taxonomy of these small organisms. During our visit
in 1986, we noted abundant insect life at many sites,
probably due to the heavy rains in previous months.
Besides hand collecting in which we recorded capture
success per unit time, we employed light traps which
attracted insects to sampling stations. We also studied
carabid beetles collected during previous expeditions
(previously unpublished data: S. Jacquemart 1974; 1.
Schatz 1985).
Our samples were identified by means of the
available scientific literature and reference material
of the two species already known from Galápagos and
especially using specimens from the Leleup Expedition
deposited in the IRSNB, Brussels (Basilewsky 1968;
Reichardt 1976). Table 1 summarizes all new data
obtained in our study, including those from the
Jacquemart and Schatz expeditions.
RESULTS
The Species and Their Distribution.--
Tachys vittiger and T. erwini are both easily
recognized by the two large pale spots on both of the
elytra (the hard winglike structures that cover the
functional wings) and the microsculpture (pattern of
sculpture only visible at higher magnification) of a
very fine mesh on the elytra. The latter species is
somewhat larger, and differs in the shape of midbody,
especially by having less pronounced posterior angles
of the pronotum.
21
A third species was encountered (Fig. 1) which can
be distinguished from the other species by the
following combination of characters: smaller in size
than T. vittiger (mean total length of 2.015 mm versus
2.163 mm for males and 2.039 mm versus 2.282 mm
for females), the presence of coarse isodiametric
microsculpture evident on the elytra; head, pronotum,
and elytra brownish-black without paler spots, the
sides of pronotum and elytra only somewhat paler;
appendages pale, except femora and penultimate
segment of palp somewhat darker. We do not know yet
whether this species is known from the continent or
elsewhere. Further study is planned to determine if
this species is new to science or is instead a species
known from elsewhere but not previously known from
Galápagos.
O.5mm
Figure 1. Dorsal view of Tachys sp., an unidentified
species only recently discovered in Galápagos. Vista
dorsal de Tachys sp., una especie recientemente
descubierto en Galápagos y todavia no identifcada.
The distribution of the three species as presently
known is summarized in Fig. 2. It is not clear if these
beetles have not been adequately sampled in
22
southeastern islands or whether they are not present
in this region. Perhaps preferred habitats are rare or
absent on these islands. The only sites where we
found T. vittiger and Tachys sp. to be abundant were
near lagoons and small ponds with brackish or salty
water especially in the coastal zones of the islands.
On this basis we suspect that one or more species will
be found in the future on Genovesa near the saline
crater lake.
~
(:) . TACI-IYS V¡ITIGER : NEWMTAQ (j)
TAONS VIIT!GER : LlTERATURE MTA
. TACHYS ERWINI : NEW DATA
111 TAONS ERWINI : LlTERAME DATA
TACHYS SPEC. 3 : NEWMTA{).
Q ct;IJ .<1'
- o d7
[.)
0
Figure 2. The distribution of Tachys species on the
Galápagos Islands. La distribución de Tachys en las
Islas Galápagos.
Flight Actlvlty.--We have noted that all
specimens of the three species examined to date by us
have possessed large hind wings and had functional
indirect flight muscles (these are the main necessary
muscles involved in wing beating during flight; in other
carabids these muscles can be absent or reduced to a
high degree) indicating an ability to fly. We have
observed each of the species in flight, but only during
nighttime hours. Moreover, we observed that high
numbers of beetles could be attracted to a light after
heavy rain showers. At least during the warm season,
beetles may avoid flight during the day due to the high
temperatures and higher risk of water loss in warm
dry air. On several occasions when flight was
observed, temperatures were recorded to investigate
possible threshold reactions of the flight activity
(Table 2). Nights with temperatures around 200C
were most productive for capturing beetles in flight;
nights with higher temperatures had fewer captures
(Table 2). On 1 night the number of beetles caught at a
light so urce in 30 minute intervals was simultaneously
compared with the mean temperature of the air over
the hours during which beetles were sampled (Fig. 3).
On the basis of these data we suggest that flight
Noticias de Galápagos, No. 46, May 1988
activity occurs within a narrow range of temperatures
at 21-240C. This conclusion is tentative, beca use we
do not have simultaneous data on humidity of the air,
wind speed, and light levels which are other possible
factors affecting flight activity of beetles. In any case
the attraction of beetles to light proves their ability to
orient their flight.
The tendency for insects to lose their flight ability
and reduce the distances moved is well-known in island
situations, and the flight ability in the diminutive
carabid beetles which we found may seem paradoxical
in this regard. We propose a simple explanation for
this failure to lose flight. The Tachys beeties in
Galápagos show a high degree of habitat preference for
edges of brackish or saline water bodies. They were
especially abundant at the borders of all salt marshes
explored by us: the lagoon near Villamil and Beagle
Crater on Isabela, the lagoons near Playa Espumilla and
Mina de Sal on Santiago. and at Turtle Bay on Santa
Cruz. The preference for such an unstable habitat that
could dry out or be inundated could have serious
consequences for the beetles inhabiting the Galápagos.
The capacity to fly enables beetles to escape from
adverse conditions. A by-product would be the
potential for colonization of new areas. The ability to
move over large distances by flying contributes to the
possibility that one or more of these beetles is likely
to occur on each Galápagos island wherever suitable
habitats exist. During or after periods with optimal
circumstances for flight, small numbers of beetles
could be found in other habitats, not just those where
the populations are most successful. This could
account for observations of T. vittiger at higher
altitudes in the Transition Zone with Scalesia and
Miconia on Santa Cruz during February 1974 and
Volcán Cerro Azul (at 700 m) on Isabela during
February 1986. For these species, flight ability
seems to be adapted to the instability of their
preferred habitats.
CONCLUSIONS
As a consequence of their flight ability,
populations of beetles on different islands are not
completely isolated and a significant amount of gene
flow may occur between relatively distant populations.
Adaptive radiation into new or markedly different
habitats may be less likely to occur in the face of
frequent interisland movements. None of the Tachys
species is restricted to a single volcano or island
within Galápagos. This is in contrast to many other
carabid beeties which have limited powers of dispersal
and are quite restricted in their distributions within
Galápagos (Desender et al., in prep.). Even though T.
vittiger is Ihe only Tachys species known from Ihe
South American mainland, the possibility exists that
38
T
E 29
H
P
E 28
R
A 27T
U
R 26E
25
2-4
23
22
21
Noticias de Galápagos, No. 46, May 1988
the other two species also occur there.
ACKNOWLEDGMENTS
Our work in Galápagos was made possible through
the financial support of the National Foundation for
Scientific Research (Belgium), the Ministry of
Education of Belgium, and the Leopold 111Foundation.
We wish to thank Ms. Sonia Sandoval and Ms. Sandra
Abedrabo for the valuable assistance in the field. We
also thank Lic. Miguel Cifuentes, Dr. Gunther Reck, Ing.
Humberto Ochoa, Dr. Giovanni Onore, and Dr. 1. Schatz
for their cooperation and assistance.
LlTERATURE CITED
Basilewsky, P. 1968. 111.Les Calosomes des lIes
Galápagos (Coleoptera, Carabidae). Pp. 179-
207 lr!. Mission zoologique beige aux iles
Galápagos et en Ecuador (N. et J. Leleup,
1964-1965). Vol. 1.
Erwin, T. 1974. Studies on the subtribe Tachyina
(Coleoptera: Carabidae: Bembidiini).
23
Supplement A: Lectotype designations for New
World species, two new genera, and notes on
generic concepts. Proceedings of the
Entomological Society of Washington 76:123-
155.
Franz, H. 1985. Beitrag zur Kenntnis der
Koleopterenfauna des Galápagos-Inseln.
Sitzungsberichten der Osterrische Akademie
der Wissenschaften. Mathematica-
naturwissenschaften. Klasse, Abteilung 1,
194:73-124.
Linsley, E.G., and R.L. Usinger. 1966. Insects of the
Galápagos Islands. Proceedings of the
California Academy of Sciences 33: 113-196.
Reichardt, H. 1976. A contribution to the knowledge
of the Carabidae of the Galápagos Islands
(Coleoptera). Pp. 179-222. in Mission
zoologique beige aux iles Galápagos et en
Ecuador (N. et J. Leleup, 1964-1965). Vol. 111.
Van Dyke, E.C. 1953. The Coleoptera of the Galápagos
Islands. Occasional Papers of the California
Academy of Sciences 22:1-181.
20 22 24
t TRAPPING PERIOD
10
2
. t
6
t
84
SUNRISE
Figure 3. Observed flight activity (vertical bars) of Tachys vittiger in relation to mean air temperatures durjng 1
night in which sampling was conducted from 2000 to 0200. Note the decrease in captures when the air
temperature rose above 230C. Actividad de vuelo (baras verticales) de Tachys vittiger en relación al promedio
de temperaturas del aire durante una noche entree 2000 y 0200. Se nota una disminución de capturas cuando la
temperatura subió arriba de 230C.
Numbers
Site Date Males/Females Situation
T. erwini
Pinta 03 Mar 86 o/ 1 beach zone, near light
T. vittiger
Isabela 24 Feb 82 8/ 3 Beagle Crater
21 Feb 86 4/ 4 lagoon, 4 km N Villamil
21 Feb 86 18/19 lagoon, Villamil
25 Feb 86 1 1 /1 1 lagoon, Villamil
23 Feb 86 o/ 1 Cerro Azul, 700 m
Rábida 09 Mar 86 1/ 2 lagoon
Santa Cruz 15 Jan 74 o/ 1 Miconia zone
07 Feb 74 o/ 1 transition zone
09 Feb 74 O/ 2 northern slope
15 Feb 74 1/ O top of island
20 Feb 85 1/ O Puerto Ayora
28 Feb 86 1/12 Darwin Station, near light
01 Mar 86 11/17 Darwin Station, near light
02 Mar 86 O/ 1 Darwin Station, near light
29 Mar 86 21/26 Darwin Station, near light
14 Mar 86 18/27 Bahía Tortuga, near light
15 Mar 86 14/20 Bahía Tortuga
Santiago 08 Mar 86 25/35 Mina de Sal
08 Mar 86 18/16 Playa Espumilla lagoons
T. sp.
Rábida 09 Mar 86 o/ 1 lagoon
Santa Cruz 15 Mar 86 5/ 5 Bahía Tortuga
29 Mar 86 o/ 1 Darwin Station, near light
24 Noticias de Galápagos, No. 46, May 1988
Table 1. New records of Tachys species in Galápagos.
Konjev Desender and Jean-Plerre Maelfalt,
laboratorlum voor Oecologie, Zoogeografie
en Natuurbehoud ledeganckstraat 35, B-9000
Gent, Belglum; Leon Baert, Konlnklljk
Belglsch Instltuut voor Natuurweten-
schappen, Vautlerstraat 29, B-1040
Brussels, Belglum.
Date
Temperature Catch Success
Site Period oRange (C) Males/Females
19 Mar 86 Pinta 1800-2200 23-30 T. erwini, 0/1
21 Mar 86 Pinta 2030-2215 24.5-27 none
28 Feb 86 Darwin Station 2200-2400 24 T. vittiger, 11/12
16 Mar 86 Darwin Station 1900-2230 27-28.5 none
29 Mar 86 Darwin Station 2000-0200 21-25 T. vittiger, 53*; T. sp., 0/1
14 Mar 86 Bahía Tortuga 2030-2130 24.5-26 T. vittiger, 10/19
14 Mar 86 Bahía Tortuga 2130-2230 24.5-25.5 T. vittiger, 8/8
Noticias de Galápagos, No. 46, May 1988 25
Table 2. Details of flight activity observed relative to ambient air temperatures.
*S pecimens in h'
were nol sexed.
t IS sample
REVIEW: FUR SEALS, MATERNAL
STRATEGIES ON LAND AND AT SEA
Edited By: Roger L. Gentry and
Gerald L. Kooyman
Publlshed 1986, 344 pages, with
illustrations. Princeton University Press,
3175 Princeton Pike, Lawrenceville, New
Jersey 08648, USA
Reviewed By: Hendrick N. Hoeck
In 1986 two outstanding books on Galápagos
species were published by Princeton University Press.
One is Peter Grant's Ecology and Evolution o( Oarwin's
Finches (reviewed elsewhere in this issue) and the
other, which is reviewed here, is Fur Seals, Maternal
Strategies on Land and al Sea in which Fritz Trillmich
and his associates present in five chapters the results
of their 10 years of research on the behavioral
ecology of Galápagos fur seals and sea lions.
In mammals, the females bear almost all the cost
of rearing the young. The long gestation and postnatal
period up to weaning is energeticallY very costly. The
mother/offspring group is therefore the key unit for
understanding the social organization in mammals.
The overall allocation of maternal energy
resources can be divided into several categories such
as foraging and travel costs, energy spent for avoiding
predators, energy loss due to parasites and diseases,
and finally milk production and maintenance
metabolism. The pattern of energy allocation to these
categories has evolved in response to environmental
pressures balanced against physiological limitations.
The book tells the fascinating story of how females
of six different species of Otariids, living in Galápagos
under tropical conditions and in the Arctic and
Antarctic under subpolar conditions, manage to raise a
maximum number of offspring. Fourteen scientists (all
experts and some with years of field experience) give
a detalled account of the behavioral ecology of
Northern, Antarctic, South African, South American,
and Galápagos fur seals and Galápagos sea lions.
Of the 15 chapters, the first gives an overview of
the evolutionary history of the species studied and a
brief description of their systematics, distribution,
and biology. The second chapter deals with methods.
Chapters 3, 6, 8, 10, 11, and 13 describe the
attendance behavior of each species, while Chapters 4,
5, 7, 9, 10, 12, and 14 describe the feeding and diving
behavior of the six species and the free ranging
energetics of the Northern fur seals. In the last and
most important chapter, nine authors integrate the
results and draw conclusions.
The Northern fur seal and the Antarctic fur seal
occur in the subpolar regions where there are extreme
cold temperatures but predictable seasonal changes. In
contrast, the Galápagos fur seal and sea lion live on
the Equator, where the seasonal changes are less
profound but are highly unpredictable. Between these
~nvironmental extremes a fur seal mother has to adapt
In order to produce a maximum number of young. The
different options and strategies that fur seal females
use are presented.


Distribution and flight activity of Carabid Beetles Genus Tachys in the Galápagos Archipelago

http://aquaticcommons.org/4759/1/NG_46_1988_Desender_et_al_Carabid_beetles_Tachys.pdf

Distribution and flight activity of Carabid Beetles Genus Tachys in the Galápagos Archipelago

Abstract

Similar works

Full text

Available Versions

Aquatic Commons