2-2 Beecher & Brenowitz Flashcards
(111 cards)
1
Q
What are songs?
A
complex species-specific signals given by animals of many taxa in mating and intrasexual contexts, most commonly by males to attract females and to repel
rival males
2
Q
In most animal taxa, these species-specific
vocal signals develop without ______ _____ ____
A
In most animal taxa, these species-specific
vocal signals develop without significant environmental
input
3
Q
Which animals learn species-specific vocal signals?
A
- humans
- cetaceans
- some bats
- three orders of birds
4
Q
Particularly striking is the
comparison of the ______ passerines and the closely related
______ passerines
A
Particularly striking is the
comparison of the oscine passerines and the closely related
suboscine passerines
5
Q
Particularly striking is the
comparison of the oscine passerines and the closely related
suboscine passerines for, although song functions in much
the same way in both groups, song is learned in the ______
but not in the _____
A
Particularly striking is the
comparison of the oscine passerines and the closely related
suboscine passerines for, although song functions in much
the same way in both groups, song is learned in the oscines
but not in the suboscines
6
Q
Evolutionary questions about song learning in songbirds originally focused on what?
A
Evolutionary questions about song learning in songbirds originally focused on the adaptive advantages of
learning song versus not learning song
7
Q
As comparative
studies of songbirds have accumulated, however, the focus
has shifted to the evolution of different song-learning
programs within the _____
A
As comparative
studies of songbirds have accumulated, however, the focus
has shifted to the evolution of different song-learning
programs within the oscines
8
Q
Songbird species differ as
to whether they what?
A
(i) learn songs in the first few months of life, over the first year, or throughout their lifetimes;
(ii) learn a single song or a repertoire of songs;
(iii) develop their song repertoires by imitating external models, by
improvising on tutor songs, or by inventing songs with
minimal reference to the external models;
(iv) require early exposure to conspecific song or can develop speciestypical song even when raised in isolation;
(v) copy only tutor songs that fit tightly constrained speciesspecific parameters or copy essentially anything they hear.
9
Q
A phylogenetic perspective
addresses what possibility?
A
A phylogenetic perspective
addresses the possibility that the different song-learning
strategies are not responses to different functional
problems, but are alternative approaches to the same
functional problem
10
Q
Song learning and production in songbirds are regulated by what?
A
Song learning and production in songbirds are regulated by a
discrete network of hormone-sensitive brain nuclei
11
Q
Song learning and production in songbirds are regulated by a
discrete network of hormone-sensitive brain nuclei [54]. This brain
network has been observed in each of the ____+ ____ species in ___
families examined thus far, but is lacking in ___ species in three
____ families that have been investigated
A
Song learning and production in songbirds are regulated by a
discrete network of hormone-sensitive brain nuclei [54]. This brain
network has been observed in each of the 60+ oscine species in ten
families examined thus far, but is lacking in seven species in three
suboscine families that have been investigated
12
Q
Inspection of the song system in different oscine taxa shows that
this neural system is uniform in _____ and ____ _______ across taxa
A
Inspection of the song system in different oscine taxa shows that
this neural system is uniform in morphology and chemical properties across taxa
13
Q
Three attributes
of the song system might enable the production of extreme
behavioral diversity by this highly conserved network of brain nuclei
what are they?
A
(i) The network appears to function exclusively in controlling
song-related behavior.
; (ii) Steroid hormones have pronounced
influences on the development and activation of these circuits.
(iii) Song is a
learned behavior and is thus subject to rapid modification via
cultural evolution.
14
Q
Three attributes
of the song system might enable the production of extreme
behavioral diversity by this highly conserved network of brain nuclei
what do the attributes potentially provide?
A
These three attributes together might provide the
plasticity that has enabled the diverse expression of song learning
across groups.
15
Q
Closed-ended learner
A
Closed-ended learner: a bird that does not modify its repertoire after the first
year. Also known as age-limited learner.
16
Q
Imitation:
A
Imitation: a song that is a good copy of a tutor song.
17
Q
Improvisation
A
Improvisation: a song that resembles a tutor song, but which is substantially
different in certain respects.
18
Q
Invention
A
Invention: a song that cannot be traced to a tutor song.
19
Q
Mimicry
A
Mimicry: copying of sounds other than conspecific song, typically heterospecific song, but sometimes non-avian or even non-animal sounds
20
Q
Open-ended learner
A
Open-ended learner: the bird modifies its song repertoire after its first calendar year.
21
Q
Repertoire matching
A
Repertoire matching: replying to a song with a different song from the
repertoire of the bird that matches a song that the stimulus bird has in its own
repertoire
22
Q
Sensitive period
A
Sensitive period: a relatively short period early in life when a bird is receptive to
song memorization
23
Q
Sensorimotor phase
A
Sensorimotor phase: phase during which a bird sings and tries to match its
output to earlier-memorized songs; follows or overlaps the sensory phase.
24
Q
Sensory phase
A
Sensory phase: phase of song learning during which the bird memorizes the
tutor song.
25
Song
```
Song: a relatively complex vocalization used in interactions with males and/or
female conspecifics. A single song (or strophe) is usually relatively short
(usually 2–4 sec) and is separated by a longer period of silence before the next
song. In some cases, birds sing more continuously and individual songs can be
quite long (e.g. 20 sec or more in sedge warblers).
```
26
Song dialect
Song dialect: song similarity over a larger geographic area (i.e. on the scale of
kilometers).
27
Song element
Song element: a song is composed of a series of contrasting elements,
arranged in the same order each time (e.g. in song sparrows and great tits) or in
unique orders every time it sings (e.g. in sedge warblers).
28
Song-learning program
Song-learning program: the genetic-developmental program thought to
underlie song learning in a species (or a race or population of a species).
29
Song matching
Song matching: replying to a song with a similar song. Pertains to cases where
bird has a song repertoire and can select a song type that is similar to the
stimulus song.
30
Song repertoire
Song repertoire: defined in terms of song types or elements. Most birds form
song elements into stable song types, but others (e.g. sedge warblers)
improvise songs from their repertoire of song elements.
31
Song sharing
Song sharing: song similarity within neighborhoods or groups
32
Song type
Song type: song types can be categorized; that is, there is less variation
within song types than between them. Also defined by singing pattern of
bird when it sings songs of one song type consecutively within a bout
(e.g. AAACCCBBBDDD.) or sings its song types with immediate variety
but in a stereotyped order (e.g. ABCDEABCDEA .).
33
White-crowned sparrow
During the sensory or
memorization phase, a young bird must hear a tutor
song and, during the _______ phase, it attempts to
match its vocal output to the songs memorized previously.
During the sensory or
memorization phase, a young bird must hear a tutor
song and, during the sensorimotor phase, it attempts to
match its vocal output to the songs memorized previously.
34
Learning can be demonstrated by isolating the bird during
the ______ phase, or by deafening it just before the
______ phase; both typically produce a bird that
sings abnormal song
Learning can be demonstrated by isolating the bird during
the sensory phase, or by deafening it just before the
sensorimotor phase; both typically produce a bird that
sings abnormal song
35
We
argue here that the diversity of oscine song-learning
programs (reviewed in [3,12]) is more extreme than is
generally appreciated, and varies along at least the
following five dimensions:
- when the song is learned (or how long the song repertoire is modified)
- how many songs a bird learns
- copying fidelity
- role of early song experience
- degree of canalization
36
The period during which birds can learn songs ranges
widely, from a brief sensitive period during the first ___ ____ __ ___ (white-crowned sparrow), to the ___ ___ ___ (chaffinch Fringilla coelebs and indigo bunting
Passerina cyanea [13,14]) to _____ ____ _____
(village indigobird Vidua chalybeata, great tit Parus
major, pied flycatcher Ficedula hypoleuca and willow
warbler Phylloscopus trochilus
The period during which birds can learn songs ranges
widely, from a brief sensitive period during the first few
months of life (white-crowned sparrow), to the entire first
year (chaffinch Fringilla coelebs and indigo bunting
Passerina cyanea [13,14]) to throughout the lifetime
(village indigobird Vidua chalybeata, great tit Parus
major, pied flycatcher Ficedula hypoleuca and willow
warbler Phylloscopus trochilus
37
The period during which birds can learn songs ranges
widely, from a brief sensitive period during the first few
months of life (___-____ ______), to the entire first
year (___ ____ ___ and ___ ___ ___ ___) to throughout the lifetime
(___ ___ ___ ___, ___ ___ ___ ___, ___ ___ ___ ___ and ___ ___ ___ ___)
The period during which birds can learn songs ranges
widely, from a brief sensitive period during the first few
months of life (white-crowned sparrow), to the entire first
year (chaffinch Fringilla coelebs and indigo bunting
Passerina cyanea [13,14]) to throughout the lifetime
(village indigobird Vidua chalybeata, great tit Parus
major, pied flycatcher Ficedula hypoleuca and willow
warbler Phylloscopus trochilus
38
Species in
which birds add songs to their song repertoires after the
first calendar year are referred to as what?
Species in
which birds add songs to their song repertoires after the
first calendar year are referred to as open-ended learners
39
Species in
which birds do not add songs to their song repertoires after the
first calendar year are referred to as
closed-ended (or age-limited) learners
40
Although ___-____ learning has generally been the
default assumption, in most cases there is no evidence to
support this
Although closed-ended learning has generally been the
default assumption, in most cases there is no evidence to
support this
41
species that we assume to be
closed-ended learners might, on closer inspection, prove to
be open-ended learners,
what is an example of this
species that we assume to be
closed-ended learners might, on closer inspection, prove to
be open-ended learners, as, for example, McGregor and
Krebs discovered for great tits
42
It is harder to prove
| that learning is closed-ended than that it is not. why?
It is harder to prove
that learning is closed-ended than that it is not, for it takes
only one bird to make the point that learning can occur
beyond the first year, but many more to make the point
that it cannot
43
In ~__% of songbird species studied, males sing multiple
| song types
In ~70% of songbird species studied, males sing multiple
| song types
44
example of a small song repertoire
chaffinch, great tit and swamp sparrow
| Melospiza Georgiana; all less than five
45
example of a moderate song repertoire
song sparrow Melospiza melodia and western
| meadowlark Sturnella neglecta; ten or so
46
example of a large song repertoire
western marsh wren Cistothorus palustris and
| common nightingale Luscinia megarhynchos; >100
47
example of a huge song repertoire
brown thrasher Toxostoma rufum, >1000
48
____- to _____-sized repertoires are most common
Small- to moderate-sized repertoires are most common
49
Several experiments in which species (song sparrows versus swamp sparrows) or subspecies (eastern versus western marsh wrens) with different repertoire sizes were raised in a common environment established that differences in repertoire size in these cases were due to what?
Several experiments in which species (song sparrows
versus swamp sparrows) or subspecies (eastern versus
western marsh wrens) with different repertoire sizes
were raised in a common environment established that
differences in repertoire size in these cases were due to
genetically based differences in the underlying songlearning programs
50
In different species (and sometimes in different populations of a species), song learners appear to vary along a
continuum, ranging from ____ , to ____ to _____.
In different species (and sometimes in different populations of a species), song learners appear to vary along a
continuum, ranging from imitation (faithful copying of
tutor song), to improvisation (variations on the tutor
material) to invention (develops species-typical songs that
bear no obvious relation to the tutor material, and which
might or might not even require song tutoring).
51
bird song learning was first demonstrated by
| showing what?
bird song learning was first demonstrated by
| showing that songbirds raised in isolation develop abnormal song
52
examples of isolation not always produce
| abnormal song.
grey catbird Dumetella carolinensis and sedge warbler
Acrocephalus schoenobaenus: these birds generate large,
normal song repertoires when raised in song-isolation
conditions
53
In white-crowned sparrows and several other species,
birds copy tutor material only if it fits tightly constrained
____-_____ _______and, in these cases, song
learning would be classified as ______ ______
In white-crowned sparrows and several other species,
birds copy tutor material only if it fits tightly constrained
species-specific parameters and, in these cases, song
learning would be classified as environmentally canalized
54
Marler and Peters [20] found that when
presented with the same tape-recorded regime of song
sparrow and swamp sparrow songs, ____ sparrows will
copy heterospecific as well as conspecific elements, but
___ sparrows will not.
Marler and Peters [20] found that when
presented with the same tape-recorded regime of song
sparrow and swamp sparrow songs, song sparrows will
copy heterospecific as well as conspecific elements, but
swamp sparrows will not.
55
Other species are capable of
copying most things that they hear, the best-known
examples being what?
- brown thrashers
- northern mocking-birds
- marsh watblers
- indian hill mynahs
- superb lyrebirds
56
____ _____ are an important but often neglected
| variable in song learning
Social factors are an important but often neglected
| variable in song learning
57
what is the tape tutor design
The ‘tape tutor’ design enables precise experimental
control of the key features of song exposure, such as timing and
dosage, and it simplifies the analysis because the experimenter
knows exactly what the bird heard and when it heard it.
58
what is a limitation of the tape tutor design
the omission of possibly the key
variable in song learning, what we loosely label ‘social factors’. The
particular songs that a bird learns could depend as much or more on
which bird is singing and how it sings, as it does on the amount and
the timing of song exposure.
59
what did Baptista and Petrinovich show
In song-learning experiments with
white-crowned sparrows, Baptista and Petrinovich [58] showed that
the rules of song learning derived from Marler’s classic experiments
with this species were stretched or broken when the song tutors
were live birds.
For example, whereas tape-tutored white crowns
reject heterospecific song and any song presented beyond 50 days,
live-tutored white crowns can learn conspecific or heterospecific
song presented after day 50
60
what did nordby find about song sparrows with live tutors?
Nordby et al. [60] found that song sparrows
tutored by live tutors learned more from late tutors (introduced after
day 150) than they did from early tutors (removed on day 90)
61
what does nordby's results contrast with?
This
outcome contrasts with an earlier tape tutor study by Marler and
Peters [61] which found early tutors to be more effective than late
tutors, with most of the songs the bird ultimately sang having been
heard before day 90.
62
Social factors
have the potential to modify the effects of all the other variables
what are some examples of this?
e.g. extend the sensitive period, make late tutors more effective than
early tutors, reduce canalization, change a bird from an improviser to
a copier, etc.
63
A new approach to reconciling the
conflicting results that have been obtained with live tutors and
tape tutors is what?
the ‘virtual tutor’: the computer presentation of
digitized song streams to an isolated young bird in a fashion
designed to simulate typical tutor–tutor and tutor–tutee song
interactions
64
Most functional hypotheses of
song, however, have focused on _______________________________________,
and have not directly addressed t______________________________________________
Most functional hypotheses of
song, however, have focused on the adult song repertoire,
and have not directly addressed the song-learning
strategy by which the bird reaches that final repertoire.
65
Song hypotheses fall into two general classes,
what are these classes
those that view song repertoire size as the target of selection and
those that view song sharing as the target.
66
According to
| the Repertoire hypothesis, __________________________________________
According to
the Repertoire hypothesis, the song-learning program is
designed to give the bird a large song repertoire
67
according to the Sharing hypothesis ________________________________________________________________________________________-
according to the Sharing hypothesis , the song-learning program is designed to give
the bird songs that it shares with its neighbors or group
members
68
There is considerable empirical support for the hypothesis that repertoire size is under strong directional sexual
selection in some songbirds
what is an example of this
The evidence comes
from several large-repertoire species and, in these cases, the evidence suggests that
repertoire size is driven by female choice
69
The applicability
| of the Repertoire hypothesis is limited, however, by what?
The applicability
of the Repertoire hypothesis is limited, however, by the
fact that most songbird species have just one or a few songs.
70
About __% of species have single-song repertoires,
| and at least another __% have very small repertoires
About 30% of species have single-song repertoires,
| and at least another 50% have very small repertoires
71
Small repertoires can
perhaps be explained as being the result of the high costs
of ___ _____, but evidence that song repertoires are
costly is limited
Small repertoires can
perhaps be explained as being the result of the high costs
of large repertoires, but evidence that song repertoires are
costly is limited
72
A related hypothesis is that a
complex network of brain nuclei devoted to ___ _____
might entail special developmental and energetic costs
A related hypothesis is that a
complex network of brain nuclei devoted to song learning
might entail special developmental and energetic costs
73
recent evidence that
brain centers involved in song learning are selectively
affected by ______ _____
recent evidence that
brain centers involved in song learning are selectively
affected by developmental stress
74
Sharing hypotheses focus on the advantages of ____ ____
Sharing hypotheses focus on the advantages of song
| sharing
75
Song sharing
is common in songbirds and is found in a variety of social
contexts, not only in ____ _____ (the most
commonly studied context), but also in ____ ____
and ____ _____
Song sharing
is common in songbirds and is found in a variety of social
contexts, not only in territorial neighbors (the most
commonly studied context), but also in lekking species
and communal breeders
76
In indigo buntings, first-year birds that ____ ___ ___ ___ ___ __ ____ ____ were more
successful in acquiring a territory, mating and fledging
young than were birds that did not
In indigo buntings, first-year birds that shared
their single song with an older neighbor were more
successful in acquiring a territory, mating and fledging
young than were birds that did not
77
average repertiore size of song sparrows in USA?
8 or 9
78
first-year song sparrows that ____ ___ ___ ___ ___ with their neighborhood group held their territories
for more years than did birds that shared fewer; by
contrast, ____ ___ did not predict lifetime territory
tenure
first-year song sparrows that shared more of their
songs with their neighborhood group held their territories
for more years than did birds that shared fewer; by
contrast, repertoire size did not predict lifetime territory
tenure
79
Another study of a different western population found a similar correlation between ____ and
song sharing
Another study of a different western population found a similar correlation between survival and
song sharing
80
In a third study of western song
sparrows, it was found that repertoire size predicted
____ ____ but not ____ ____ in a bird’s first
year [37]; song sharing was not measured in this study.
In a third study of western song
sparrows, it was found that repertoire size predicted
mating success but not territory acquisition in a bird’s first
year [37]; song sharing was not measured in this study.
81
three studies about song sparrows taken together suggest what?
three studies taken together suggest that, in
western song sparrows, female choice might select for
large song repertoires and male–male competition might
select for song sharing.
82
what is the Dear Enemy hypothesis
long-term neighbors are preferred to newcomers
because newcomers are inherently expansionist, whereas old
neighbors generally respect territory boundaries once they have
been mutually established
83
how does Dear Enemy hypothesis apply to songs
. Neither preferring nor cooperating with
familiar neighbors requires shared songs, but shared songs are a
reliable signal (a ‘badge’) of familiarity or locality because they must
be learned in the local neighborhood.
84
what did a study find to support the dear enemy hypothesis?
a recent study [64] found that neighboring song sparrows
sharing fewer songs were more aggressive with one another than
were neighbors sharing more songs.
85
A corollary of the Dear Enemy hypothesis for territorial songbirds
is that established neighbors should use their songs in place of _____- and _____-_____ physical interactions to minimize unnecessary
territorial conflicts
A corollary of the Dear Enemy hypothesis for territorial songbirds
is that established neighbors should use their songs in place of timeand energy-costly physical interactions to minimize unnecessary
territorial conflicts
86
Playback studies of song sparrows and banded
wrens have supported this prediction
what did they find
birds
use their mix of shared and unshared song types to form a graded
signaling system for mediating territorial interactions. Even when
neighbors do not share any song types (with respect to the
investigators’ criterion), they might still be able to song match
using songs in their repertoires that they perceive as being most
similar
87
A song
sparrow typically engages a neighboring bird by singing one of the song types
that they share. The neighbor then either does what?
(i) returns a directed but low-threat
signal by repertoire matching; that is, by replying with a shared type other than
the one that the neighbor just sang; or
(ii) escalates the interaction by song
(type) matching; that is, by replying with the same song type as the neighbor
just sang; or
(iii) de-escalates by replying with an unshared type
88
Song learning designed to
maximize the number of songs copied from a set of birds,
the ‘tutors’, (such as, for example, the present neighbors)
cannot also maximize what?
Song learning designed to
maximize the number of songs copied from a set of birds,
the ‘tutors’, (such as, for example, the present neighbors)
cannot also maximize the percentage of songs shared with
this or a similar set of birds (e.g. the future neighbors).
89
It is also the case that such a
learning preference for tutor-shared songs will
increase the chance that the song learner will still share
songs with tutor-neighbors even if what?
It is also the case that such a
learning preference for tutor-shared songs (e.g. the songs in
the top rows versus those in the bottom row of Figure 1) will
increase the chance that the song learner will still share
songs with tutor-neighbors even if some of those neighbors
die ormove away
90
The Sharing hypothesis also provides a novel perspective on the difference between closed-ended and openended learners
what is this?
If the ‘goal’ of a bird is to develop songs
that are similar to those of its neighbors, then an openended learner could add and drop songs each year so as to
increase song sharing with its new neighbors.
91
If the ‘goal’ of a bird is to develop songs
that are similar to those of its neighbors, then an openended learner could add and drop songs each year so as to
increase song sharing with its new neighbors.
what is the support for this?
Such a
pattern has been observed in several species examined so
far [15,34,39–42].
A similar result has been found for birds
that change their song in the beginning of their first or
second breeding season [13,43,44].
92
why should the optimal repertoire size be smaller for open-ended learners?
the optimal
repertoire size should be smaller for open-ended learners
than for comparable closed-ended learners, because openended learners have the opportunity to replace nonmatching songs with matching songs.
Contrariwise, a
closed-ended learner does not have the ability to change
its repertoire to increase sharing, but if it has more songs
to begin with, it has a better chance of finding a suitable
match.
93
most of
the open-ended learners that replace songs to increase
sharing have ____ _____ than do comparable
closed-ended learners
most of
the open-ended learners that replace songs to increase
sharing have smaller repertoires than do comparable
closed-ended learners
94
Kroodsma [12] has argued that, for birds without longterm neighbors, there is no advantage to _____ ____,
and so the development of ____ ____-_____ ____ will be favored.
Kroodsma [12] has argued that, for birds without longterm neighbors, there is no advantage to shared songs,
and so the development of generalized species-typical
songs will be favored.
95
Northern
populations of sedge wrens are migratory and seminomadic during the breeding season, and so an individual
has a constantly changing set of neighbors. When tutored
with taped song, what happened?
When tutored
with taped song, North American sedge wrens do not
imitate these songs but rather improvise or invent songs,
all of them normal species songs
96
North American sedge wrens do not
imitate these songs but rather improvise or invent songs,
all of them normal species songs [47].
the
closely related but sedentary marsh wrens faithfully did what?
By contrast, the
closely related but sedentary marsh wrens faithfully copy
tutor songs in comparable experiments, and in the field they
share songs with their neighbors.
97
tropical
populations of sedge wrens, which unlike the semi-nomadic
northern populations are _____, show the common
pattern of song sharing with neighbors that is generally
taken to imply song learning from neighbors
tropical
populations of sedge wrens, which unlike the semi-nomadic
northern populations are sedentary, show the common
pattern of song sharing with neighbors that is generally
taken to imply song learning from neighbors
98
we suggest that the best
approach to understanding these different learning
strategies will be to view them in a ______ context
we suggest that the best
approach to understanding these different learning
strategies will be to view them in a phylogenetic context
99
Price and Lanyon [50] looked for a correlation
between the intensity of ____ ____ (measured as
____ ____) and ____ ____ in the oropendolas
and caciques.
Price and Lanyon [50] looked for a correlation
between the intensity of sexual selection (measured as
sexual dimorphism) and song complexity in the oropendolas
and caciques.
100
Price and Lanyon [50] looked for a correlation
between the intensity of sexual selection (measured as
sexual dimorphism) and song complexity in the oropendolas
and caciques.
what did they detect?
They detected effects of sexual selection and
found that different aspects of song were affected in different
lineages.
101
Irwin [52] found that variation
| in song repertoire size was not explained by ____ _____ ____ in New World ______ (Icterinae),
Irwin [52] found that variation
in song repertoire size was not explained by directional
sexual selection in New World blackbirds (Icterinae),
102
In a study of
emberizine sparrows (Emberizinae), Irwin [53] found the
most parsimonious hypothesis to be _____________________________________________, indicating
that there had been selection for ______________________________________
In a study of
emberizine sparrows (Emberizinae), Irwin [53] found the
most parsimonious hypothesis to be that the common
ancestor of these species was a repertoire species, indicating
that there had been selection for smaller repertoires in
several of these species (including the one-song whitecrowned sparrow)
103
Handley and Nelson [49] examined 65
populations in the family Fringillidae.
What did they find?
They found that song
sharing or song dialects evolved rapidly in response to local
conditions, being responsive to whether the species was
migratory or sedentary and to breeding latitude (higher
song sharing for sedentary species and low breeding
latitudes).
Local song sharing was randomly distributed
on the phylogeny.
Repertoire size and song sharing were
uncorrelated, consistent with the hypothesis that they are
responsive to different selective forces.
104
These new phylogenetic studies have been aptly
| summarized by Price and Lanyon:
‘Song appears to
provide multiple potential targets for selection . and as
a consequence, different evolutionary patterns have
emerged in different lineages
105
We suggest that a
| profitable line of future research will be to plot what?
We suggest that a
| profitable line of future research will be to plot characteristics of song learning on songbird phylogenies.
106
A phylogenetic analysis might reveal what?
A
phylogenetic analysis might reveal, as these recent
analyses suggest, that song-learning programs have
evolved along different trajectories in different lineages
107
what is the only real impediment in phylogenetic analysis?
At this point,
the only real impediment to the proposed project is the
lack of data on song learning as compared to the much
larger database on song traits such as repertoire size.
108
Song learning evolved early during the _____ _____ and
| led to ____ ____ and _____ __ _____.
Song learning evolved early during the oscine lineage and
| led to enhanced complexity and diversity of song.
109
The diversity of song-learning
strategies in oscine species varies on at least five dimensions
what are they
(i) closed-ended versus open-ended learning;
(ii) repertoire size;
(iii) imitation versus improvisation
versus invention;
(iv) external versus internal song models;
(v) selective song learning versus mimicry.
110
The most difficult problem for functional hypotheses is presented by what?
The most difficult problem for functional hypotheses is presented by different oscine lineages
responding to similar selection pressures with different
modifications of the song-learning program.
111
The most difficult problem for functional hypotheses is presented by different oscine lineages
responding to similar selection pressures with different
modifications of the song-learning program.
what is an example of this
For example, perhaps the song-learning programs of sedge warblers and marsh wrens have been driven by sexual selection to the same goal of developing a large song repertoire. But if so, then the differences in the song-learning programs of these two species – one requiring external song models and the other not – might best be explained not in terms of different selection pressures but in terms of different ancestries.
