Behavioral Ecology Vol. 13 No. 2: 188-192
© 2002 International Society for Behavioral Ecology
Does paternity or paternal investment determine the level of paternal care and does female choice explain egg stealing in the fifteen-spined stickleback?
Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, S-752 36 Uppsala, Sweden
Address correspondence to S. Östlund-Nilsson, who is now at VTHRC, University of Queensland, Brisbane, Queensland 4072, Australia. E-mail: saraon{at}mailbox.uq.edu.au .
Received 17 February 2001; revised 16 May 2001; accepted 16 May 2001.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
An earlier field study on the fifteen-spined stickleback (Spinachia spinachia) showed that frequent male—male interactions result in high frequencies of sneaking and egg stealing. Moreover, sneaking behavior was performed not only by males adopting alternative mating strategies, but also by males with their own nests. The advantage of sneaking is easily understood, but it is more difficult to explain the evolutionary benefit of stealing eggs from other males. I investigated whether males suffering from sneaking adjust their paternal effort in relation to their degree of paternity. I also examined whether females prefer males that have more eggs in their nests, as this could explain egg stealing. There was no relationship between the degree of paternity and fanning activity, hatching success, or nest defense. However, the older the eggs become, the more the males increase their attack rate toward potential egg predators (goldsinny wrasse and shore crabs). Thus, males adjusted their level of defense to the amount of energy and time already invested in the clutch. Females did not prefer males with more eggs in their nests. On the contrary, females preferred males with reduced clutches over males with enlarged clutches. Therefore, female choice is unlikely to be a driving force behind egg stealing in this species.
Key words: egg stealing, female choice, paternal investment, paternity, Spinachia spinachia, sticklebacks.
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
Parental care is costly in many ways (for reviews, see Clutton-Brock, 1991
;
Smith and Wootton, 1995).
According to many studies, the effort a male expends on parental care is
positively correlated with the certainty of paternity
(Davies et al., 1992;
Møller and Birkhead,
1993; Sargent,
1989; Sheldon and Ellegren,
1998), but this is not always the case
(Svensson et al., 1998;
Whittingham and Lifjeld 1995).
Reasons that the certainty of paternity and paternal care do not always go
hand in hand may differ (for review, see
Owens, 1993).
In fish males most often provide care for the offspring, when care at all
is provided (Blumer, 1979;
Gross and Sargent, 1985). In
the fifteen-spined stickleback Spinachia spinachia, the male alone
cares for the eggs by fanning and guarding them until they hatch, which takes
about 3 weeks. The male also spends a lot of metabolic energy on producing
protein threads (Hentschel,
1977,
1979; Östlund-Nilsson,
unpublished data), which he wraps around a ball of filamentous algae to form a
safe nest for the eggs.
A field study on the fifteen-spined stickleback (same population as in this
study) established that nesting males frequently suffer from sneaking and egg
stealing (Jones et al., 1998).
Sneaky fertilizations in fish are often performed by small males as an
alternative reproduction strategy. These males may be too small to compete
successfully with larger males for females or territories. In the
fifteen-spined stickleback this may partly be the case, but microsatellite
assessment revealed that sneaking also was performed by males that had their
own nests and territories in the neighborhood
(Jones et al., 1998).
I investigated how sneaking and egg stealing affects paternal care. First, does male parental effort (such as fanning frequency and predator defense) correlate with the level of paternity? Second, why do males steal eggs from other males? Whereas the evolutionary advantage of sneaking is obvious, this is hardly the case for the deliberate adoption of eggs from another male's nest. However, if females show a preference for males with many eggs in their nests, eggs may function as a nest ornament and render egg stealing as an advantageous strategy.
|
METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
The investigation was carried out from early May to July in 1998 at Klubban Biological Station, Fiskebäckskil, on the west coast of Sweden (58°15' N, 11°28' E). Fifteen-spined sticklebacks were collected locally from a depth of 1-6 m in Fucus and Zostera vegetation by snorkeling and by hand-trawling. Females were placed together in 250-l aquaria, approximately 10 females in each aquarium. All aquaria were continuously supplied with water pumped from the sea; temperature (11°-16°C) and the light followed diurnal cycles. Fish were fed twice a day with minced mussel meat, frozen or live mysid shrimps, and live Artemia.
Male parental investment in relation to paternity
All males were put singly in an aquarium of 50 1 (1 x h x w =
0.5 x 0.4 x 0.25 m) with opaque screens surrounding the walls of
every aquaria. I ran 10 trials, each with 3 males that differed in the degree
of paternity as follows: (1) full-paternity males mated alone with a female;
(2) shared-paternity males shared paternity with another male. This was
accomplished by introducing another male (a sneaker) into the male's aquarium
when he was about to mate with the female. This resulted in both males
simultaneously fertilizing the eggs. Because both males were in the nest at
the same time and nesting male himself had to chase the other away from the
nest before I removed the sneaker, the nesting male was aware of the sneaker
and therefore aware of his shared paternity. (3) No-paternity males had no
paternity at all. To achieve this I manually switched the entire clutches
between two freshly mated males.
Two paternal care activities were examined: egg fanning and predatory
defense. I observed the fanning behavior of the males every third day with the
first observation on the day after males had received the egg clutches in
their nests. Fanning behavior in this species has been shown to correlate with
hatching success (Östlund and
Ahnesjö, 1998). Every fanning bout was considered to start
when the male's pelvic fins began to beat, and end when the male stopped
fanning and began to swim around. I measured fanning bout duration, number of
fin beats during fanning, the duration of the pause between fanning bouts, and
water temperature. For each male the fanning observation was performed on 10
fanning bouts every third day. I then calculated a mean fanning bout time
(seconds), fanning beat frequency (fin beats per second), pausing time
(seconds), and fanning bout frequency (number of fanning bout durations +
pauses per hour) from all the observations on every third day for each male.
From those mean values I then calculated a mean value for every male and for
his complete brooding cycle. When the fry hatched I counted them and released
them into the sea. Hatching success was calculated by dividing the number of
hatched fry with the initial number of eggs in the clutch. To obtain the
latter value, I took three eggs from the clutch and measured the wet mass of
the eggs (4.0 ± 1.0 mg per egg for all clutches), and I assumed that
the clutch mass was the same as the female's mass loss during spawning (mean
± SD = 1.34 ± 0.35 g for all females).
Another measurement of paternal effort is the intensity with which the father defends his offspring. I measured defense behavior three times during the period between mating and hatching to see whether males were more eager to defend older broods. The first measurement was made on the day after mating, the second after 12 days, and the last when the fry started to hatch (days 19-21). I used two species of nest predators: goldsinny wrasse (Ctenolabrus rupestris; length, 64.9 ± 9.0 mm; mass, 5.9 ± 3.1 g) and shore crabs (Carcinus maenas; length over the widest part of the back, 31.1 ± 6.0 mm; mass, 8.2 ± 6.0 g). In the field I have seen both predators eating eggs in fifteen-spined stickleback nests. New wrasses and crabs were used for each male at each time. I put one wrasse at a time in a small, transparent plastic bag, with small holes to allow the male to both see and smell the predator. The bag was rapidly moved through the middle of the water column and stopped for 10 s when it was 40, 30, 20, and 10 cm from the nest. At each stop I counted the number of aggressive attacks toward the wrasse (biting the bag). The crab was tied to a transparent plexiglass stick using a rubber band. I forced the crab rapidly to "walk" on the bottom toward the nest and stopped it at the same distances and intervals as the fish predator, counting the number of attacks by the male at each distance. I let 6 h pass between introducing either predator, and I randomly changed the order that the two species of predators were introduced (crab or wrasse first). After the trials the predators were released back in the sea.
Mate choice on eggs in nest
I let females choose between three males that had different clutch sizes in
their nests. The males did not differ in mass (males with no eggs in the nest:
5.2 ± 1.4 g, males with half clutch: 5.0 ± 1.4 g, males with 1.5
clutch: 5.3 ± 1.3 g, oneway ANOVA, F2,30 = 0.32,
p =.73) or length (no eggs in the nest: 115.7 ± 12.5 mm, half
a clutch: 110.6 ± 9.6 mm, 1.5 clutch: 114.1 ± 9.7 mm, one-way
ANOVA, F2,36 = 0.77, p =.47) within each
replicate. In each replicate, the three males had their newly built nests
removed. Then they were each given a nest from another male to adopt. The size
and age of all three adopted nests were the same. After each male had mated
with a female in the adopted nest, I removed the eggs completely from one
male. I mixed and distributed the eggs from the other two males so that one of
them received half a normal clutch (about 0.70 g) and the other a clutch about
1.5 times the size of an normal egg clutch (about 2.0 g). I mixed the eggs
from the clutches to avoid differences in egg quality influencing female
choice. I placed the males in a large outdoor tank, 1300 l (1.7 x 0.8 m)
with a water depth of 1 m. The males were separated by an opaque screen
(Figure 1). Males were enclosed
in 40-l transparent plastic bags overnight to acclimatize. I then leashed each
male by placing a 3-mm wide piece of cling wrap gently around his body, close
to the pelvic fins. Then I knitted a thin fishing line (0.10 mm diam) to the
cling wrap and attached the other end of the line to a little piece of cork,
which in turn was connected with the same type of line to the top of an
adjacent aquarium wall. By leashing the males I excluded male—male
interactions and allowed the females to freely inspect the males and their
nests. Leashing stickleback males does not negatively affect courtship or
mating (Östlund-Nilsson,
2000; Östlund-Nilsson and
Nilsson, 2000). After the female had seen all the males in the
tank (which took about 5 min), I observed her for 30 min. I considered a male
to be preferred if she spawned with him (n = 8), or, if spawning did
not occur within the 30-min observation period, if he received more intensive
female courtship that the other males (n = 5). Female courtship was
quantified as the sum of the number of times she (1) swam up to the male and
(2) put her head into the nest.
|
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
Fanning effort
When comparing males with different degrees of paternity (no, shared and full; Table 1), there was no significant difference in fanning duration (one-way ANOVA, F2,26 = 0.025, p =.97), fin beat rate (ntot = 27, Kruskal-Wallis test, K = 1.25, p =.53), fanning bout frequency (one-way ANOVA, F2,26 = 0.14, p =.87), pause duration (one-way ANOVA, F2,26 = 0.42, p =.66), male mass loss (one-way ANOVA, F2,24 = 0.42, p =.66), hatching success (one-way ANOVA, F2,27 = 0.021, p =.98), or water temperature (one-way ANOVA, F2,26 = 1.24, p =.31).
|
Predator defense intensity
The intensity of predator defense against goldsinny wrasses did not vary
with the degree of paternity (two-way ANOVA, F2,71 = 1.10,
p =.34; Figure 2a),
but the defense intensity increased significantly over time as eggs developed,
regardless of paternity level (two-way ANOVA, F2,71 =
18.6, p <.0001; Figure
2a).
|
The same pattern was found with shore crabs. Although defense did not vary with paternity (two-way ANOVA, F2,71 = 1.14, p =.33; Figure 2b), it increased as eggs grew older (two-way ANOVA, F2,71 = 8.97, p =.0003; Figure 2b). See Figure 2 for mean values and for paired tests within the treatments.
The increase in attack rate over time was unrelated to water temperature, as temperature was constant (day 1, 14.1° ± 1.5°C; day 20, 14.6° ± 1.4°C; n = 27, paired t test, t = 1.3, p =.20). Moreover, the three paternity groups did not differ with regard to temperature on day 1 (no paternity, 14.0° ± 1.5°C; shared, 14.1° ± 1.6°C; full, 14.0° ± 1.6°C; one-way ANOVA, F2,27 = 0.014, p =.99), on day 12 (no paternity, 15.0° ± 0.33°C; shared, 14.9° ± 0.42°C; full, 15.2° ± 0.60°C; one-way ANOVA, F2,25 = 0.90, p =.42), and on day 20 (no paternity, 14.8° ± 1.5°C; shared, 14.3° ± 1.5°C; full, 14.8° ± 1.1°C, one-way ANOVA, F2,24 = 0.42, p =.66).
Female choice and clutch sizes
Females did not prefer any particular clutch size (chi-square test,
2 = 2.9, p =.19;
Figure 3). However, when
comparing males with reduced clutches (pooled data for no clutch and half a
clutch) with males with enlarged clutches, females preferred males with
reduced clutches (two-tailed binomial test: p =.022;
Figure 3).
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
The results showed that as the eggs in the nest grew older, the males increased their intensity of attacks against potential nest predators. This suggests that the males are able to adjust their paternal investment according to the amount of energy and time they have put into the egg clutch. Other studies have shown that males are more alert when defending more valuable broods (Magnhagen and Vestergaard, 1991
,
1993). Nevertheless, the males
did not adjust their paternal effort in relation to the degree of paternity.
Thus, with regard to fanning and defense, males with full paternity did not
invest more effort in their clutches than males that had experienced sneaking
(shared paternity) or more than males that had their whole clutch fertilized
by another male (no paternity). A straightforward explanation for this is that
a male of this species simply cannot distinguish between eggs he fertilized
and eggs another male fertilized. Perhaps this explains why sneaking is so
common in this species (revealed by the previous field study on paternity in
this population; Jones et al.,
1998). Had mechanisms evolved to reduce the effort spent on
cuck-olded clutches, sneaking behavior would presumably be less common. A lack
of relationship between paternal effort and paternity is also evident in other
fish, such as the common goby Pomatoschistus microps
(Svensson et al., 1998).
Many studies have indicated that females of several fish species prefer to
spawn in nests with many eggs (Forsgren et
al., 1996; Goldschmidt et al.,
1993; Knapp and Sargent,
1989; Kraak and Videler,
1991; Marconato and Bisazza,
1986; Ridley and Rechten,
1981; Sikkel,
1989; Unger and Sargent,
1988; but see Jamieson and
Colgan, 1989). If a female diluted her own eggs with eggs from
other females, she may reduce the risk that all her eggs will be preyed upon
by a predator or through filial cannibalism. Moreover, by selecting a nest
that already contains many eggs, a female may copy the choice of other
females, thereby reducing the cost involved in searching for a suitable male
(Kraak, 1996). In the
three-spined stickleback (Gasterosteus aculeatus), females have been
shown to prefer nests with many eggs, and this has been the classical
explanation for why males engage in egg stealing in this species
(Goldschmidt et al., 1993;
Mori, 1995;
Rohwer, 1978). Still, Jamieson
and Colgan (1992) did not find
that egg stealing increased the fitness of the raiders.
In this study I could not find a female preference for many eggs in the nest. On the contrary, females preferred no or few eggs in the nest compared to an oversized clutch. There may be disadvantages involved in choosing males with many eggs. In the fifteen-spined stickleback the eggs are not spread out in a thin layer, but instead the egg clutch has a compact, globular shape, which would increase the risk of hypoxia for eggs positioned centrally in an oversized clutch. Another disadvantage of choosing a nest full of eggs would be that competition with an older brood, in which the male has already invested both time and energy, might occur. Such a male may be physically more exhausted and starved compared to a male with an empty nest, so perhaps he will abandon the nest after the first clutch has hatched or cannibalize the new clutch.
In the absence of female preference for egg-filled nests, another
explanation for the egg-stealing behavior of males could be that they use the
clutch as a food supply. However, the present data suggest that the male
cannot recognize their own eggs and would therefore run the risk of consuming
their own offspring. Still, it is possible that a male can recognize the
stolen clutch by its position in the nest. I have on several occasions in
field seen egg clutches on the outside of the nest. Perhaps the male
deliberately positioned them separately to use as food. Mass loss is a
consequence of reduced food intake during the paternal phase, as caring
shortens the time available for food searching
(Magnhagen, 1986;
Marconato et al., 1993;
Okuda and Yanagisawa, 1996;
Sabat, 1994;
Wiegmann and Baylis, 1995), a
situation that may trigger filial cannibalism
(Marconato et al., 1993;
Okuda and Yanagisawa, 1996),
so stealing and eating the eggs of other males may substantially increase a
male's own reproductive success.
The costs of paternal care in the fifteen-spined stickleback exceed just fanning and defense. The males also produce protein threads, which serve as glue, maintaining the structural integrity of the nest and keeping the eggs within the nest. These threads are also attractive to females because by preferring nests with much tangspiggin (i.e., protein threads), they ensure that the father is in a good nutritional status (Östlund-Nilsson, unpublished data). Moreover, starved males have a reduced rate of protein production, suggesting that these protein threads are metabolically costly to produce (Östlund-Nilsson, unpublished data). Thus, males may have yet another reason to steal eggs for food.
In conclusion, males increase their paternal effort as the value (age) of the brood increases. Increased paternity did not increase paternal effort, so males may value clutch age (i.e., time and energy invested into the offspring) more than the degree of paternity. Females showed no preference for more eggs in the nests, and this cannot therefore be a mechanism explaining why nesting males steal eggs from one other.
|
ACKNOWLEDGEMENTS |
|---|
I am grateful to Anders Berglund and Göran Nilsson for valuable comments on the manuscript. Financial support was provided by Uppsala University (Inez Johansson Foundation and the Foundation for Zoological Research), the Royal Swedish Academy of Science (Hierta-Retzius Foundation), and the Helge Ax:son Johnsson foundation. I thank Klubban Biological Station for putting their facilities at my disposal. This study followed the ethical guidelines for animal experiments at Uppsala University.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
Blumer LS, 1979. Male parental care in the bony fishes. Q Rev Biol 54: 149-161.
Clutton-Brock TH, 1991. The evolution of parental care. Princeton, New Jersey: Princeton University Press.
Davies NB, Hatchwell BJ, Robson T, Burke T, 1992. Paternity and parental effort in dunnocks Prunella modularis: how good are male chick-feeding rules? Anim Behav 43: 729-745.
Forsgren E, Karlsson A, Kvarnemo C, 1996. Female sand gobies gain direct benefits by choosing males with eggs in their nests. Behav Ecol Sociobiol 39: 91-96.[Web of Science]
Goldschmidt T, Bakker TCM, Feuth-de Bruijn E, 1993. Selective copying in mate choice of sticklebacks. Anim Behav 45: 541-547.[Web of Science]
Gross MR, Sargent RC, 1985. The evolution of male and female parental care in fishes. Am Zool 25: 807-822.
Hentschel H, 1977. The kidney of Spinachia spinachia (L.) Flem. (Gasterosteidae, Pisces) 1. Investigations of juvenile sticklebacks: anatomy, circulation and fine structure. Z Mikrosk-Anat Forsch Leipzig 91: 4-21.
Hentschel H, 1979. The kidney of a teleost, Spinachia spinachia II. Histochemical identification of sialic acid-containing glycoprotein and fine structure of mucus secreting cells. Tissue Cell 3: 517-531.
Jamieson IG, Colgan PW, 1989. Eggs in the nests of males and their effect on mate choice in the three-spined stickleback. Anim Behav 38: 859-865.[Web of Science]
Jamieson IG, Colgan PW, 1992. Sneak spawning and egg stealing by male threespine sticklebacks. Can J Zool 70: 963-967.
Jones A, Östlund-Nilsson S, Avise J, 1998. A microsatellite assessment of sneaked fertilizations and egg thievery in the fifteen-spined stickleback. Evolution 52: 848-858.[Web of Science]
Knapp RA, Sargent RC, 1989. Egg mimicry as a mating strategy in the fantail darter, Ethiostoma flabellare, females prefer males with eggs. Behav Ecol Sociobiol 25: 321-326.[Web of Science]
Kraak SBM, 1996. "Copying mate choice": which phenomena deserve this term? Behav Process 36: 99-102.[Web of Science]
Kraak SBM, Videler JJ, 1991. Mate choice in Aidablennius sphynx (Teleostei, blennidae): females prefer nests containing more eggs. Behaviour 119: 242-266.
Magnhagen C, 1986. Activity differences influencing food selection in the marine fish Pomatoschistus microps. Can J Fish Aquat Sci 43: 223-227.
Magnhagen C, Vestergaard K, 1991. Risk taking in
relation to reproductive investment and future reproductive opportunities:
field experiments on nest-guarding common gobies, Pomatoschistus
microps. Behav Ecol 2:
351-359.
Magnhagen C, Vestergaard K, 1993. Brood size and offspring age effecting risk-taking and aggression in nest-guarding common gobies. Behaviour 125: 233-243.[Web of Science]
Marconato A, Bisazza A, 1986. Males whose nests contain eggs are preferred by female Cottus gobio L. (Pisces, Cottidae). Anim Behav 34: 1580-1582.
Marconato A, Bisazza A, Fabris M, 1993. The cost of parental care and egg cannibalism in the river bullhead, Cottus gobio L. (Pisces, Cottadie). Behav Ecol Sociobiol 32: 229-237.[Web of Science]
Møller AP, Birkhead TR, 1993. Certainty of paternity covaries with paternal care in birds. Behav Ecol Sociobiol 33: 261-268.[Web of Science]
Mori S, 1995. Factors associated with and fitness effects of nest-raiding in the three-spined stickleback, Gasterosteus aculeatus, in a natural situation. Behaviour 132: 1011-1023.[Web of Science]
Okuda N, Yanagisawa Y, 1996. Filial cannibalism by mouthbrooding males of the cardinalfish, Apogon doederleini, in relation to their physical condition. Environ Biol Fish 45: 397-404.
Östlund S, Ahnesjö I, 1998. Female fifteen-spined sticklebacks prefer better fathers. Anim Behav 56: 1177-1183.[Web of Science][Medline]
Östlund-Nilsson S, 2000. Are nest characters of importance when choosing a male in the fifteen-spined stickleback (Spinachia spinachia). Behav Ecol Sociobiol 48: 229-235.[Web of Science]
Östlund-Nilsson S, Nilsson GE, 2000. Free choice by female sticklebacks: lack of preference for male dominance traits. Can J Zool 78: 1251-1258.
Owens IPF, 1993. When kids just aren't worth it: cuckoldry and parental care. Trends Ecol Evol 8: 269-271.
Ridley M, Rechten C, 1981. Female sticklebacks prefer to spawn with males whose nests contain eggs. Behaviour 76: 152-161.[Web of Science]
Rohwer S, 1978. Parental cannibalism of offspring and egg raiding as a courtship strategy. Am Nat 112: 429-440.[Web of Science]
Sabat AM, 1994. Costs and benefits of parental effort
in a brood-guarding fish (Ambloplites rupestris, Centrarcidae).
Behav Ecol 5:
195-201.
Sargent RC, 1989. Allopaternal care in the fathead minnow, Pimephales promelas: stepfathers discriminate against their adopted eggs. Behav Ecol Sociobiol 25: 379-385.[Web of Science]
Sheldon BC, Ellegren H, 1998. Paternal effort related
to experimentally manipulated paternity of male collared flycatchers.
Proc R Soc Lond B 265:
1737-1732.
Sikkel PC, 1989. Egg presence and developmental stage influence spawning-site choice by female garibaldi. Anim Behav 38: 447-456.
Smith S, Wootton RJ, 1995. The cost of parental care in teleost fishes. Rev Fish Biol Fish 5: 7-22.
Svensson O, Magnhagen C, Forsgren E, Kvarnemo C, 1998. Parental behaviour in relation to the occurrence of sneaking in the common goby. Anim Behav 56: 175-179.[Web of Science][Medline]
Unger LM, Sargent RC, 1988. Allopaternal care in the fathead minnow, Pimephales promelas, female prefer males with eggs. Behav Ecol Sociobiol 23: 27-32.[Web of Science]
Whittingham LA, Lifjeld JT, 1995. High paternal investment in unrelated young: extra-pair paternity and male parental care in house martins. Behav Ecol Sociobiol 37: 103-108.[Web of Science]
Wiegmann DD, Baylis JR, 1995. Male body size and paternal behaviour in smallmouth bass, Micropterus dolomieui (Pisces: Centrarchidae). Anim Behav 50: 1543-1555.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  O. Svensson and C. Kvarnemo Parasitic spawning in sand gobies: an experimental assessment of nest-opening size, sneaker male cues, paternity, and filial cannibalism Behav. Ecol., March 1, 2007; 18(2): 410 - 419. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Rios-Cardenas and M. S. Webster Paternity and paternal effort in the pumpkinseed sunfish Behav. Ecol., September 1, 2005; 16(5): 914 - 921. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. B. Steinhart, M. E. Sandrene, S. Weaver, R. A. Stein, and E. A. Marschall Increased parental care cost for nest-guarding fish in a lake with hyperabundant nest predators Behav. Ecol., March 1, 2005; 16(2): 427 - 434. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||