Download Bats

‘Ope’ape’a: The Hawaiian
Hoary Bat
• Overview of the subspecies
• Upcoming Research
• Echolocation and moth auditory sensory
evolution
• Ebola update
Morphological Studies
Suggest Relative of Mainland
Hoary bat
 Lasiurus cenerius
cenerius (North
American)
 L. c. vittosissimus
(South American)
 L. c. semotus
(Hawaiian)
Hawaiian Hoary Forest Species
• Mainland species also forest species
-utilizes tree roost in native forest
-commonality still remains overtime
-Hawaiian hoary could be good indicator species
• Strange findings in lava tube on Mauna Loa
• Variable habitat range
-found in wet and dry areas of the island
-from sea level to 13,000 ft
• Mean home range (consisting of several disjunct activity centers and
the day roost)
-males 121 ha
-females 5.6ha
Inaccurate population
counts
 Most current
population counts
based on sightings
 Difficulties with
Anabat II
 Future intraspecific
echolocation analysis
 The importance of
microphone location
Mainland hoary’s rather
lengthy migration
Only terrestrial mammals to reach
Hawaii
Hawaii—A great place to study
evolutionary trends
Morphological Comparisons
between L. c. cinerius and L. c.
semotus
• Character divergence:
-flight
-feeding
-45% decrease in
body size
Microchiropteran utilize
echolocation during hunting
Potential drawback—
May alert prey of
impending attack
Researchers find it
difficult to quantify
information
The Hawaiian archipelago is an
ideal place to examine moth
hearing as a bat predation defense
• Only one bat species known to exist on
the islands
• L. c. semotus exerted entire predatory
selection pressure on the ears of
sympatric moths.
L. c. semotus prey preferences

Endemic vs. adventive moths

Why is H. euclidias preferred over similar
sized endemic moths?

Effects of artificial lighting
Insect nervous system auditory
processing center evolution
• Ears have appeared
19 times in the class
Insecta
• Fundamentally similar
structures
• Common selection
pressure (bat
predation)
Moth ears—neurologically
simple
• Consist of up to four auditory receptors
• It has been proposed that the closeness of the
bat as perceived by the moth determines the
bimodal defense flight behavior
5 acoustic stages in
foraging echolocation:
1.
2.
3.
4.
5.
Search
Approach
Tracking
Terminal Buzz (I)
Terminal Buzz (II)
The moth also has certain
neurological stages that somewhat
correlate to the approaching bat
behavior
Stage #1: The most sensitive
receptor, A1
The moth directionally detects with its most
sensitive receptor, A1, a foraging bat that
is echolocating in a searching mode-----responses of A1 evoke controlled directional
flight away from the bat so that the bat does not
have a chance to detect the moth.
Second defense mode

Bat echolocating in tracking or terminal
buzz mode
-As bat approaches target, alters the duration,
intensity, frequency, and structure of calls
- Acoustical reason for this (avoidance of pulseecho overlap)
A1 and less sensitive A2 receptor activated
 Triggers erratic flight pattern

A1 receptors encodes bat calls as a
near bat until 100-200 ms before
the attack

disactivation of interneurons and a
premature cessation of near-bat
responses.
-little selection pressure to maintain vigorous A1
response for the final ms of a moth’s life?
-may be an adaptive tactic used by the bat to
facilitate captured of eared moths
A2 receptor may be vestigial and
not used in flight response
May play a role in a
different bat
defense—sound
emission (echo
jamming effect
Function of the B cell
• may in fact be vestige of a homologous
proprioceptor in thoracical earless moths
• persistence in eared noctuid moths is
reflection of low evolutionary cost of
simple nervous systems
So if moths evolved ability to
avoid bat predation, shouldn’t
they eventually lose this
ability when relieved from bat
predation pressures?
Four suggested conditions that
must be met before phenoypic
effects of bat release will occur:
1. Complete isolation from bats
2. Absense of alternative uses for ears
3. Genetic isolation from bat-exposed
conspecifics
4. Sufficient evolutionary time in batreleased condition
Bats in the news: Ebola resevoirs?
• Scientists have long wondered where the
ebola virus hides between outbreaks.
-fast killer, so often covers tracks quickly
-primates die from infection
• Maybe it’s the bats
Researchers have injected bats
with the virus and they have
survived, but only recently have 3
fruit bats been found in nature with
genetic sequences from the virus
or evidence of an immune
response to it.
Traces of the virus were found in
the animals' liver and spleen
Maybe it’s the birds…
the outer protein shell of filoviruses, such as
Ebola, have a biochemical structure similar to
retroviruses carried by birds, making a common
evolutionary origin more likely.
Until more is known public
education is important in
preventing the spread of the
disease