Atypical Acorns Appear to Allow Seed Escape After Apical Notching by Squirrels

McEuen, Amy B.; Steele, Michael

doi:10.1674/0003-0031(2005)154[0450:aaatas]2.0.co;2

Cited by 19 publications

(19 citation statements)

References 12 publications

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“…Black bars intact seeds, white bars pruned roots, gray bars pruned seeds and hashed bars embryoremoved seeds. ***P \ 0.001 Steele 2005;Steele 2008). However, the frequency of multi-seeded acorns is very low (less than 3% in oak populations), and embryo excision was likely to be a selective force for maintaining multi-seeded acorns within oak populations (McEuen and Steele 2005).…”

Section: Discussionmentioning

confidence: 98%

“…***P \ 0.001 Steele 2005;Steele 2008). However, the frequency of multi-seeded acorns is very low (less than 3% in oak populations), and embryo excision was likely to be a selective force for maintaining multi-seeded acorns within oak populations (McEuen and Steele 2005). Besides, this trait in oaks may also be maintained by insects (e.g., Curculio), not solely by squirrels (McEuen and Steele 2005;Steele 2008).…”

Section: Discussionmentioning

confidence: 99%

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High regeneration capacity helps tropical seeds to counter rodent predation

et al. 2011

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Rapid germination of non-dormant seeds is one adaptation plants have evolved to counter seed predation by rodents. Some rodent species have evolved behaviors that prevent or slow the seed germination process through seed embryo removal or seed pruning; however, no plant species is known to have successfully escaped embryo removal or seed pruning by rodents. Here, we report that the non-dormant seeds of Pittosporopsis kerrii Craib in tropical rain forests in China have a high regeneration capacity to counter seed pruning by rodents. We found seed pruning, instead of embryo removal, was commonly used by rodents to increase food storage time by slowing down the seed germination process, but that P. kerrii seeds have a high regeneration capacity to escape seed predation by rodents: all pruned seeds, pruned roots and embryo-removed seeds by rodents or people retain the ability to develop into seedlings. Seeds of P. kerrii also have other capacities (i.e. rapid seed decomposition and indigestible dormant taproots) to escape predation by reducing the plant's attractiveness to rodents. The association between seed pruning behavior in rodents and high regeneration capacity of pruned seeds or roots in P. kerrii seeds are likely novel adaptation strategies adopted by seeds and rodents, respectively.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

High regeneration capacity helps tropical seeds to counter rodent predation

et al. 2011

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“…Small mammals play a dual role both as seed dispersers and seed predators in the mutual interaction with plant species bearing large-sized seeds (McEuen and Steele 2005). Many small rodents and bird species mitigate seasons of food shortage by hoarding seeds in their caches or larders to use as long-term food supplies (Jansen et al 2006; Moore and Swihart 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Acorns of many white oak species germinate in autumn soon after they fall (Fox 1982;Hadj-Chikh et al 1996;Steele et al 2001a, b;Xiao et al 2009), resulting in food loss because nutritional reserves in acorn cotyledons are quickly transported into an inedible robust taproot (Fox 1982;Steele et al 2001a;Jansen et al 2006;Xiao et al 2009). Previous studies in the New World (Elliott 1978;Fox 1982;McEuen and Steele 2005;Steele et al 2001aSteele et al , 2007 have shown that various rodent species in different systems can slow or stop germination of cached seeds of particular fast-germinating tree species by pruning the radicle or sprout, or even by removing the entire embryo (Vander Wall 1990;Jansen et al 2006;Xiao et al 2009). Naïve tree squirrels are found to attempt embryo excision (Steele et al 2006), supporting a hypothesis that squirrels show specific behavioral adaptations to quick germination of acorns of white oak species.…”

Section: Introductionmentioning

confidence: 99%

Repeated radicle pruning of Quercus mongolica acorns as a cache management tactic of Siberian chipmunks

Yang

2011

acta ethol

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Many rodents hoard seeds as a means of ensuring food availability during scarcity. Siberian chipmunks (Tamias sibiricus) feed on acorns of white oak Quercus mongolica and hoard them for future use. Such caches may deteriorate due to the early germination of the acorns in autumn, which can be inhibited by radicle pruning or embryo excision. Siberian chipmunks are found to frequently prune the radicles of germinated acorns of Q. mongolica; however, whether this behavior is a kind of cache management tactic remains unclear. Here, we performed semi-natural enclosure and field experiments to test the role of radicle pruning in cache management of T. sibiricus. We found that T. sibiricus preferred non-germinated acorns and tended to prune radicles of germinating acorns when scatter-hoarding them, but did not perform the behavior of embryo excision by squirrels. Both semi-natural enclosure and field experiments showed that T. sibiricus not only pruned radicles repeatedly but removed radicles varied in length from acorns, which significantly postponed acorn germination and radicle growth. These observations suggest that radicle pruning would be an evolutionary tactic for cache management of Siberian chipmunks.

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“…These squirrel species have evolved specific behavioral strategies in which they selectively remove the embryo of non‐dormant acorns from white oaks prior to hoarding. Compared to intact non‐dormant acorns (>90%), acorns with the embryo removed have a lower germination success (<20%) and thus can be preserved in long‐term storage (Fox ; McEuen & Steele ; Xiao et al. ; Xiao & Zhang ).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity to Seed Germination Schedule by Scatter‐Hoarding Pére David's Rock Squirrels During Mast and Non‐Mast Years

2013

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Mast seeding by oaks (Quercus) and other seed species has fundamental impacts on the behavior of individual scatter-hoarding animals as well as their population and community dynamics. Scatter-hoarding squirrels are highly sensitive to acorn germination schedule and stop germination by removing the embryo of non-dormant acorns to prevent losses of energy and nutrients by rapid germination. However, we know little about how this behavior is affected by mast seeding. We investigated foraging decisions made by free-ranging P ere David's rock squirrel (Sciurotamias davidianus) with three species that produce non-dormant seeds and two species that produce dormant seeds (Fagaceae) during mast and non-mast years in Central China from 2007-2010. Consistent with the food perishability hypothesis that squirrels make decisions to minimize the perishability of their caches, non-dormant seeds were hoarded at a lower rate, but had a higher probability of embryo removal than dormant seeds. Compared with non-mast years, a lower proportion of seeds were harvested during mast years, but a higher proportion of the harvested seeds were hoarded. In addition, the probability of embryo removal in the hoarded seeds was higher during mast years. Squirrels also dispersed seeds at shorter distances during mast years. Moreover, the interactions between mast seeding and seed germination schedule had significant effects on squirrel foraging decisions, including embryo removal. This study is the first to demonstrate that squirrels show greater sensitivity to seed germination potential when seeds are abundant.

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Atypical Acorns Appear to Allow Seed Escape After Apical Notching by Squirrels

Cited by 19 publications

References 12 publications

High regeneration capacity helps tropical seeds to counter rodent predation

High regeneration capacity helps tropical seeds to counter rodent predation

Repeated radicle pruning of Quercus mongolica acorns as a cache management tactic of Siberian chipmunks

Sensitivity to Seed Germination Schedule by Scatter‐Hoarding Pére David's Rock Squirrels During Mast and Non‐Mast Years

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